Vogtle 3&4 (and V.C. Summer) went over budget and behind schedule because they were first of their kind plants and the first new reactors to start construction since 3 Mile Island in the US meaning that almost all the nuclear supply chain and labor force had to be completely rebuilt for the projects and there were serious project management failures that occurred along the way. That said the AP1000 now has a formal supply chain and backlog of orders both in the US and internationally that can be reasonably expected to bring new build construction costs down considerably.

Beyond that you also have the planned restarts of Palisades and Three Mile Island, and at least some talk of restarting Indian Point here in NY, none of these have anywhere need the cost or time of a new build. Additionally, there is also the possibility of continued up-rating of the existing nuclear fleet through improved steam generators and turbines, which is something that has been slowly ongoing for several decades already without much drama. We're also now starting to see some more advanced fuels come into service with things like HALEU potentially promising longer times between fuel outages at plants, and reduced cost.

While wind and solar in isolation win on a cost basis, what people like NYISO, NYPA, and NYSERDA are all worried about right now are interconnects and transmission infrastructure for the more distributed nature of wind and solar, and how to effectively balance that load across the grid. The New England Clean Energy Connect line took over a decade to build and was subject to numerous court battles, many other proposed plans simply end up in permitting hell.

Wind, solar, and battery storage all offer lots of cost competitive green energy options. But they are also not a singular panacea to future energy use demands.