The Australian grid shows that when solar is the dominant part of the grid, it can still work pretty well. But you need to plan for when the sun is not shining and adapt to the notion that base load translates as "expensive power that you can't turn off when you need to" rather than "essential power that is always there when needed". The notion of having more than that when a lot of renewables are going to come online by the tens of GW is not necessarily wise from a financial point of view.
That's why coal plants are disappearing rapidly. And gas plants are increasingly operating in peaker plant mode (i.e. not providing base load). Also battery (domestic and grid) is being deployed rapidly and actively incentivized. And there are a lot of investments in things like grid forming inverters so that small communities aren't dependent on a long cable to some coal plant far away.
The economics of all this are adding up. Solar is the cheapest source of energy. Batteries are getting cheap as well. And the rest is just stuff you need to maintain a reliable energy system. None of this is cheap but it's cheaper than the alternative which would be burning coal and gas. And of course home owners figuring out that solar + batteries earn themselves back in a few short years is kind of forcing the issue.
Australian grid prices are coming down a lot because they are spending less and less on gas and coal. The evening peak is now flattened because of batteries. They actually have negative rates for power during the day. You can charge your car or battery for free for a few hours when there's so much solar on the grid that they prefer to not charge you than to shut down the base load of coal/gas at great cost. Gas plants are still there for bridging any gaps in supply.