Probably not the next decade. I've seen fusion researchers referred to as "the cathedral builders of our time"—their work will take decades, and they might not see success within the span of their careers, or even lifetimes.

But yes, controlled, sustained, repeatable fusion reactions could be a black swan on the order of the internal combustion engine for the 21st century.

Fusion isn't so hard. What's hard is getting a reaction big enough for "breakeven", which means getting more energy out than you put in. From there, it's even harder to capture that energy in a useable form and then use that energy to continue the reaction. So, fusion isn't so hard. Useful fusion is hard.

It would probably be the most significant technological development in human history thus far.