If things don't move on costs for significant periods of time that is typically not a good sign for future cost reductions in the same technology.
Nuclear never had a strong fall costs that is what makes it a tougher thing because you likely need a change in technology.
There are some reasonably well understood cost evolution in technology.
Wanting to spend huge amounts of money in the hope that the economics will somehow work out is not an easy proposition when other things are already cheap.