Comcast (NASDAQ: CMCSA) has made its intent clear: it's finally going to bring its DOCSIS 3.1-based gigabit broadband services to five cities this year, a move that directly challenges AT&T (NYSE: T) and Verizon (NYSE: VZ) and their FTTH buildout and pricing strategies.

Following initial launches in Atlanta and Nashville, Comcast will bring the service to Chicago, Detroit and Miami later this year.

Details about pricing and availability are lacking, but a company executive did confirm during a fourth-quarter 2015 earnings call that Comcast will be rolling out the service throughout a large part of its cable footprint.

"Concerning DOCSIS 3.1, as you know, we announced five cities yesterday, and we haven't priced the rollout yet," said Neil Smit, president and CEO of Comcast Cable, during the fourth quarter earnings call, according to a Seeking Alpha transcript. "But we -- the great thing about DOCSIS 3.1, it's a very efficient way to deliver gigabit speeds, and we'll be rolling it out on a widespread basis over the course of the next few years."

There are a few points that make Comcast's DOCSIS 3.1 service interesting.

For one, it's targeting all markets where AT&T is also offering its GigaPower 1 Gbps service. AT&T itself, the very next day after Comcast's announcement, said that it would expand GigaPower in four large metros.

But what's even more compelling from a capital investment point of view is that Comcast can deliver those gigabit speeds over its existing hybrid fiber-coax (HFC) plant. Unlike FTTH, the operator does not have to build out fiber and install facilities at each house or business to deliver service.

Comcast said it will equip customers with the services by having them plug in a new modem with gigabit capabilities once the speed tier is available in a particular area.

Still, Comcast's DOCSIS 3.1 drive isn't without its challenges. In order to get more out of their DOCSIS 3.1 deployments, cable infrastructure vendor Arris told investors during the recent Goldman Sachs Technology & Internet Conference 2016 on Wednesday that cable operators will have to drive fiber deeper into their last mile network, upgrade to 1.2 GHz nodes, and split nodes.

Given the density of Comcast's HFC plant and the growing availability of DOCSIS 3.1 equipment, Comcast will be able to scale the service widely across its footprint at a rapid clip, driving new competition at AT&T's and Google's gigabit broadband programs.

As it moves its gigabit rollout forward, Comcast could use the DOCSIS 3.1 services to battle Verizon in its nine-state Northeast territory. Verizon's FiOS network will be concentrated in the Northeast after it completes the sale of its wireline assets in Florida, California and Texas to Frontier Communications this year.

Verizon has already well penetrated its existing markets with FiOS, and with no plans for new builds, the service provider is giving customers to the option to purchase a 100 Mbps symmetrical FiOS service for $69 a month. Of course, there are a few catches with Verizon's offering: it's only good for one year without a contract and customers have pay a $150 set-up charge as well as paying other related fees, taxes and equipment charges.

Given the demand for higher speeds, Verizon is also making 50 Mbps its FiOS broadband default speed.

These moves are part of Verizon's effort to protect its FTTH broadband base as FiOS growth levels off as it reaches saturation in its existing markets. Evidence of this trend was seen in its fourth quarter 2015 results. While it did add 99,000 new FiOS Internet subscribers, it was far lower than the 145,000 Verizon added in the same period a year ago.

Since the DOCSIS 3.1 gear runs on its coax plant, Comcast could use this rollout as an opportunity to win back customers or attract new ones in Verizon's territory who are outside of the FiOS footprint.

That may be an easy case for Comcast to make, but the pay-TV operator will have to play it right -- especially when it comes to price.

Consider the fact that Comcast's 2 Gbps FTTH Gigabit Pro service comes at a premium rate of $299 a month. Customers who take the service must commit to a two-year contract. They also have have to pay a one-time $1000 fee -- a price that includes $500 for installation and $500 for service activation.

If Comcast is serious about getting a large group of customers to buy their gigabit broadband e-services, the cable MSO will have to offer them at an affordable price.

By pricing them right, Comcast has the opportunity to force the pricing hand of AT&T and Verizon. Already, Google Fiber (NASDAQ: GOOG) has been able to do this in markets like Austin, Texas, where AT&T offers GigaPower.

As Comcast reveals pricing and plans for broader DOCSIS-based services, it will be interesting to see how fiber-based broadband providers respond.--Sean

This column was updated on Feb. 11 with information on how cable will have to drive fiber deeper into its network.