(CNN) The Syrian regime's near capture of eastern Aleppo changes the face of the country's horrendous civil war; the fortunes of the many rebel groups arrayed against it have rarely seemed so bleak. But few observers expect them to sue for peace or lay down their arms.

A new phase of the conflict beckons, one in which the government led by Bashar al-Assad tries to consolidate its gains, as ruthlessly as it wishes, while its ever-more radicalized opponents revert to insurgent tactics.

All the while, any prospect of repairing the country or allowing its millions of displaced and expelled to return home remains distant. Assad will reign over a wasteland. To the head of Britain's foreign intelligence service, Alex Younger, "In Aleppo, Russia and the Syrian regime seek to make a desert and call it peace."

Rebel victory impossible

Rebels surged into much of Aleppo in 2012. As recently as the summer of 2015 they still imagined they could defeat Assad. No longer: So long as he has Russian and Iranian backing, victory for any rebel alliance is impossible. Militarily, Assad has the wind in his sails and has repeatedly said his ultimate goal is to free every inch of Syria from "terrorists."

Assad knows that's a long way off. He told the state newspaper al Watan this month that victory in Aleppo would transform the course of the conflict: "But let's be realistic," he said, "it won't mean the end of the war in Syria."

A reminder of that came as the last bastions of resistance in Aleppo began to crumble. Some 280 kilometers to the south, ISIS launched an attack on the town of Palmyra surprising in its scale and intensity. Over the weekend, Syrian troops fell back from the town, despite intense Russian airstrikes in their support. Their humiliation came just nine months after the regime celebrated retaking Palmyra and its fabled Roman theater.

Intelligence analysts Flashpoint Partners say ISIS' attack on Palmyra is a reminder of just how fluid the battlefield remains in parts of Syria. "It affords ISIS further opportunities to advance in Homs province. The group has already seized several gas and oil fields in the city, further underscoring ISIS' pursuit of energy resources."

Assad may soon control Syria's major urban centers -- or their ruins -- but vast areas of north and eastern Syria remain beyond his grasp. His armed forces have been degraded by incessant fighting, and debilitated by desertion. He must rely on irregular militia known as the National Defense Forces. More significantly, he continues to need Russian airpower and largely Shia paramilitary units from Lebanon, Iran, Iraq and Afghanistan.

Pacifying the Aleppo area will consume already-stretched resources. Jihadist rebel groups, principally the former al Qaeda affiliate now known as Fatah al Sham, still dominate the northwestern province of Idlib. ISIS still holds Raqqa and much of Deir Ezzour near the Iraqi border. The Kurdish YPG militia controls much of the border with Turkey and the sizable towns of Qamishli and Hasakah. And the hinterland around the capital Damascus is a checkerboard.

The conditions for a political solution simply don't apply. Even in its direst moments -- in mid-2015 -- the regime did not contemplate concessions. Now with the upper hand, it has no incentive to make a deal. And the international environment is arguably more favorable to the regime than it has been since 2011.

As the situation in Aleppo changes rapidly, CNN will update the map with information from sources on the ground.

Merciless battle

A US administration that repeatedly said peace in Syria was impossible while Assad remained in power is about to give way to one that wants to cooperate with Russia against terrorism in Syria. US support for the Syrian Kurds as an effective ally against ISIS may diminish. Iran has more money to spend thanks to the nuclear deal and the lifting of sanctions. Iraqi Shi'ite paramilitaries have said that once they are finished with ISIS in their own country, they will help rid Syria of terrorists (for which read Sunni groups).

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Moscow is already comparing the Obama administration to what it hopes for under a Trump administration. Speaking about the loss of Palmyra, Russian presidential spokesman Dmitry Peskov said, "Cooperation would have probably allowed us to more effectively avoid such attacks from terrorists."

The merciless battle for Aleppo has only concentrated the sectarian toxin that has steadily seeped into the Syrian civil war. It has deepened the despair of rebel groups -- and tens of thousands of trapped civilians -- of ever getting any support from the international community. But so deep is their hatred of the regime for its targeting of hospitals and indiscriminate use of barrel bombs that many have said they prefer death to surrender.

The West's response to the pulverizing of Aleppo has been confined to humanitarian appeals and strong words of condemnation at the United Nations, routinely vetoed by Moscow. The European Union said it had no plans to impose additional sanctions against Russia, with foreign policy chief Federica Mogherini saying Monday, "There was no member state asking for additional work on sanctions."

Assad and the Russians could carry on bombing with impunity. There was no threat or warning of retaliation.

With nowhere to go, moderate rebel factions are likely to make deals with radical Islamist groups -- especially in Idlib -- just to survive. Some may be absorbed into more militant factions. MI6 chief Younger said that "in defining as a terrorist anyone who opposes a brutal government, [Syria and Russia] alienate precisely the group that has to be on side if the extremists are to be defeated."

Complex considerations

The blitzkrieg against Aleppo may change the calculations of states with a dog in Syria's fight. Russia has transformed the course of the war and forged an understanding with Iran, Assad's other principal ally. If he is true to his campaign rhetoric, President-elect Donald Trump will be less inclined to support moderate rebel groups than was the Obama administration, and averse to any entanglements that go beyond striking ISIS. Of moderate rebels, he has said: "We have no idea who these people are."

For the rebels, much will depend on the attitude of regional states that have supported the Sunni resistance -- Qatar, Saudi Arabia and Turkey -- as well as the wealthy Gulf donors that have kept Islamist groups afloat.

The Qataris appear to have made their mind up. "It doesn't mean that if Aleppo falls we will give up on the demands of the Syrian people," Foreign Minister Sheikh Mohammed bin Abdulrahman al-Thani told Reuters last month.

Turkey has more complex considerations. President Recep Tayyip Erdogan has invested heavily in repairing relations with Vladimir Putin, but Turkish-backed moderate rebel groups are expanding the area under their control north of Raqqa, ISIS' capital in northern Syria. Erdogan has said recently he remains committed to Assad's ouster, but he is less vocal about it than he used to be.

America at a crossroads

US Rep. Adam Schiff, a Democrat from California, says the United States is at a crossroads. He told the Washington Post : "There will be significant reputational costs with our allies in the region if we abandon support of the moderate opposition."

The question now was "whether our Gulf allies can count on us or they can't, whether the Iranians are going to be given free rein or they won't," Schiff said.

One source with extensive contacts inside the country, and who has already lost two family members in the fighting, predicted in 2011 that a conflict in Syria would last a decade and cost a million lives. He was widely ridiculed at the time, but five years later at least 250,000 people have been killed and millions displaced.

Lebanon's civil war lasted 15 years before Saudi diplomacy, Syrian "peacekeepers" and discreet US mediation put an end to it. Those same parties are on opposite sides of this conflict, which dwarfs the scale of the Lebanese war.

The deep hatreds unleashed in the Syrian conflict, the absence of any trust and the hollowing-out of any moderate presence, as well as the continued involvement of outside powers in arming different proxies, suggest the war has years to run.