My proposal would be to use combined cycle gas turbines to peak renewables until over-installation and storage make that no longer necessary.

Gas is the cleanest fossil fuel. Modern gas turbines are by far the most efficient way of generating electricity from fossil fuels. Replacing fossil fuels burnt in ICEs and for heating with electricity generated using gas will drastically reduce emissions quickly. There is plenty of gas. Much of it is cheap to extract.

The strategic reasons for doing this are that gas turbines will be able to handle the extreme 'duck curves' and other demand volatility we will see when both renewables and electric vehicles are ramped up hard. Those are the two levers which are currently easiest to push on - because individuals can replace vehicles and heating systems, and will do so given smallish financial incentives. And because solar, wind and storage, can be scaled easily without excessive top-down planning or insane capital needs.

If nuclear is to be the solution, we have to quickly commit to it hard as a society. Compared to gas, nuclear will both make electricity more expensive and make swings and volatility in demand or in renewable supply more costly to deal with. It will on the margin discourage EV and electric heating, and discourage other renewables.

Nuclear is good at 'base load', but not much else. This is fine(-ish) if we rapidly switch to almost all nuclear. It works well in a 'Star Trek economy' where governments can act quickly and cheaply and impose choices by offering abundance. If this was the case, it would make sense to call a 50 year decision that nuclear with a modest amount of over-provision will replace almost all generation. (This has succeeded historically only in France, a very centralized economy for a Western democracy, with a high degree of regulation, and where the government has abundant access to capital.)

The real climate/energy economy is not like this. If you want to see an example of rapid change in action, look at the fracking revolution in the United States. Small players who saw opportunities created a whole new set of technologies, techniques and practices. They did this because they could react to incremental incentives. They didn't have to win everywhere at once. They could win field by field, installation by installation. We need the situation for new renewable generation and power storage to work like this. We need it to be the case that someone who provides storage in the right place at the right time can make money from it. We need it to be the case that someone who makes batteries (or gas storage or gravity storage or turbines or EVs) slightly cheaper or more efficient can make money from that.
There is no reason why this type of progress can work for environmentally damaging tech like fracking and not for environmentally beneficial tech.

Gas isn't a 50 year decision, more like a 20 year decision. It reduces emissions a lot in the short term but leaves the playing field wide open for further rapid and drastic reductions in the longer term.

(A subsidiary concern but still a real one: if you could press a button and replace all fossil fuels with reliable and safe nuclear, you would instantly have catastrophic political breakdown in places where societal cohesion depends on money from fossil fuels. Moving from oil to gas and then ramping down gas progressively allows these places to gradually develop other incomes, and allows the rest of the world time to deal with them and political problems which they are likely to export.)_