Ethereum

Thear is 2015.  If you had the same level of confidence that you have today, in formal verification.... would you still believe in client diversity?

Maschinen Krieger, scale models and the occasional Gundam. 

Ethereum Core Dev - Besu - PG4LYFE

I'm honestly not sure. I think it would still bring valuable perspective from a range of developers that think differently in different languages. But it would also be playing on hardmode; everything is harder and more expensive, in exchange for less likely bugs. If Formal Methods can also give us that.... idk