Good question, that one can only speculate on. IMO it's a two part question.

First is that newly built nuclear plants are expensive. So the question depends on if we bite the bullet (build the reactor) today or in 2070. One built today will produce cheap power in 50 years.

For example in Finland we have reactors from 1980, that make up the backbone of stable energy production in our country. Those are going to be kept online till the 2050s. I'd argue at that point the cost per kwh will be mostly dependent on maintenance and fuel, so relatively small.

Wind and solar cannot reap the same benefits if you have to replace the plant every 20 years.

Storage is a completely separate question that is not taken into account when new wind farms and such are being built. If one was to account for storage today, the cost of renewables would be much closer to that of other means of production.

Also in the future, if storage costs keep falling due to billions of R&D money, similar effects could be achieved in nuclear via serial production and scale.

EDIT: Just read you have studied this stuff for real. Then ignore most of what I said, as you might know better :D

It was started a decade ago and finished now, not in the 2070s

I would say it’s not the BEST solution but in areas in the extreme north/south, where solar/hydro aren’t options (and I legit have no idea how well wind would do with freezing weather/snow etc) it would be better to have nuclear there than to try and transmit long distance to those areas. At least until we get some more breakthroughs in energy storage.