Going to overextend myself here.
“Cold” fusion is real. But like solar, not economically viable for large scale power generation.
Functional “hot” fusion changes the world.
Given that Ford worked on direct gasoline injection combustion engines for >40 years before having them reach production (Yeah, M-B had done it in the 300SLs in the 50’s), Fusion might take a few more decades before reaching commercial success.
““Cold” fusion is real”
So far no one has produced a cold fusion system. Every last one claimed to work has been a scam.