Well, the nuclear folks need a healthy dose of economics, because nuclear is not price competitive with current solar/wind, and those generation modes are still improving 10-20% per year on LCOE.
So even if some super good nuclear reactor design was finalized, proposed, funded, and constructed on a wide basis, we're looking at, what, 10 years?
10 years of solar/wind likely improving at LEAST 5-10% per year. Compounded. Meanwhile, the nuclear industry almost always blows the budget, and if there's one thing modern America hasn't fixed its government budgets from being boondoggled.
I'm a pro-nuclear person, I believe that price-matured wind/solar can be competed with using a future reactor design, hopefully one that is scalable, meltdown proof, uses all the fuel/no waste, can breed from thorium, nonfissile uranium, or long-term nuclear waste, AKA a LFTR/MSR, although I admit those have real challenges.
We should probably keep existing nuclear functioning as load leveling on the grid, and continue aggressive funding of research/development of test reactors. But there really isn't a price competitive design in nuclear out there.
And fusion? Pfft. Even if they can sustain a reaction, I highly doubt they'll even get to fission LCOE costs, and fusion isn't as clean as people think, those fast neutrons degrade/irradiate the confinement equipment.