This will be the case some day, with perhaps some renewables we don't even think of right now thrown in. But in the next 20 years or so, it's definitely solar, wind, then gas (yes, I hate that too, but it's WAY better than coal or wood, etc) plus batteries.
The real limit here is batteries. When we have enough batteries, we can start retiring the gas. But it's going to be an economic decision. At some point it will cost 1 cent more to keep a gas system running than to set up enough batteries to handle things, and on that day it'll flip. But when it's 1 cent cheaper to have gas, they'll keep gas. And making that 1 cent judgment has to include costs you wouldn't even think of -- like buying votes, cleaning land after gas generator removal, and free publicity. Remember the gas systems are built already, staffed already (and the staff in those places is more than at battery sites and votes for what their bosses tell them to), and have defined risks that no one sued them for last year, making the chances that they'll win any new lawsuit higher, etc. It's complex.
(Note that in general, gas, which has a whole supply chain from drilling to refining to moving it around to burning it requires people -- and those people can be used as leverage when getting things from the government. Example: AT&T/Bell was famous for not automating in Illinois to keep head-count high. "Give us this rate hike/loan/stock grant for executives easement, or we'll put X of your voters out of work.")
The movement towards renewables + batteries with no gas is not really stoppable. But it's going to take time. And while we fight for it, we need to attack complex realities, not just "Well, DUH!" even though that's now clearly fundamentally right.
The terrible news which is actually good news is that the people running these systems do not give a damn about profits after they leave. At some point, giving them a golden parachute to do the right thing can accomplish this. They won't care that the leverage and obscene profits will dry up, if they are personally set.