With the announcement that Microsoft would partner with the truly open-source, Android-based Cyanogen OS to provide a bundled suite of apps, both companies made one thing very clear: Android’s not just for Google anymore.

The partnership, as detailed by Cyanogen yesterday, will allow the budding mobile OS to integrate Microsoft apps like Outlook, Office, Skype, Bing, OneDrive, and OneNote. The subtext here is that these apps can act as a replacement for the ones that Google appends to its Android releases, such as Gmail, Maps, Hangouts, and more.

Google’s obviously not the only company to preload phones on its platform with home-grown software; every iPhone comes with dozens of apps installed long before you ever power it on, and Windows Phone devices ship with plenty of Microsoft-made live tiles in place. But the increasing creep of apps you can’t uninstall, regardless of whether you want or need them—or if there are better alternatives out there—is one of the motivating forces behind the all-open-everything Cyanogen business model.

Opening Up

Dissociating Android from Google sounds great in theory but leaves several gaping holes in the user experience—holes that Cyanogen will now attempt to fill with bizarro-world Microsoft counterparts. Importantly, though, Cyanogen OS won’t shove Microsoft-owned Skype down your throat; according to spokesperson Vivian Lee, the apps will be “surfaced contextually,” meaning they’ll be presented as an option when it seems like they might be helpful, but you’ll also be welcome to use whatever else instead. You can also uninstall them at will, unlike the unkillable apps tethered to Apple and Google devices.

Lee also confirmed to WIRED that the partnership won’t affect existing devices, meaning a future update won’t mess up your OnePlus One workflow by swapping your Google apps for a Redmond imposter.

For Cyanogen, the benefit is clear: Choice is its best point of differentiation. But it also doesn’t mean much without a wide variety of options from which to choose. The Microsoft deal is just one (albeit large) step towards having as many partners on board as there are mobile developers. “Cyanogen is committed to opening up Android.” said Lee, “[It’s] predicated on user choice as an operating system.” The defining ethos here isn’t that Microsoft alone will act as an anti-Google; it’s that Microsoft will help populate the broadest mobile ecosystem available, an expansive nature reserve next to everyone else’s walled gardens.

What's In It for Microsoft

The more interesting question might be what Microsoft gets out of the arrangement. After all, it has its own mobile platform to worry about in Windows Phone, which nearly five years after first launching still hasn’t made an appreciable dent; according to the most recent Comscore numbers, it ended January with a US market share of just 3.6 percent.

That failure to gain traction may be why Microsoft has recently embraced a push to put its software on its more popular rivals. Outlook launched earlier this year on both iPhone and Android, while its Office suite went free on iOS and Android last November.

What’s even better than trying to establish an app beachhead in highly contested territory, though, is becoming the default app on a relatively new platform with lots of potential for growth. By working closely with Cyanogen, Microsoft now essentially has its own Android OS, which gives it a potential reach far greater than its own homegrown platform has found so far.

No Hardware, No Cry

The best part is that Microsoft won’t have to rely on its own devices to succeed. Lee says there are “no plans” for Microsoft Cyanogen hardware at present. Even so, any OEM that wants to hedge against Google’s increasing dominance without sacrificing the Android experience will have to at least consider Cyanogen OS, especially after the breakout success of the OnePlus One. Even if that only means a handful of low-cost devices for the time being, those are potential Bing and Skype and Outlook users that Microsoft would have otherwise been unlikely to reach.

One last wrinkle worth mentioning? Thanks to a trove of patents, Microsoft has Android licensing agreements that amount to billions of dollars of revenue every year, including a billion from Samsung in 2013 alone. Presumably as Android proliferates in whatever form, so too will Microsoft’s potential patent profits.

That’s a lot of upside with not much to lose, especially given the recent cross-platform push. And an arrangement like this makes more sense than the $70 million investment Microsoft was rumored to make back in January. Cyanogen doesn’t have to feel beholden to one software suite, and Microsoft limits its financial exposure and Windows Phone conflicts.

It’s going to be a while before we see products that realize the vision Cyanogen and Microsoft have laid out, and even longer before Cyanogen OS becomes more than a product that floats on the margins. But the news gives legitimacy to the idea that iOS might not be Google’s only serious competition for long. A more open Android is on the rise, and Microsoft just provided a powerful updraft.