Nuclear is costing a fortune in legacy costs safeguarding the waste, and its only getting worse as more and more is generated. We should invest in deep drilling techniques for geothermal and put $$$$$$$$$$ into fusion research.
The problem with saying "oh that was an old design, things are safe now", is that if you amortize the plants over a smaller lifespan, the cost skyrockets to even more than it is now (already the most expensive method of generation, and that doesn't even include legacy/cleanup costs). Guarentee when those "old" plants were originally proposed, the funding was looked at over a 40+ year lifespan. You can't expect to just rebuild the plants every 20 years because better designs have come along.