The science says, 2-3x is pretty much a done deal. There are a lot of challenges to productize and that will take time but there are so many independent companies and research groups coming up with different ways to dot this that I feel confident saying at least one of them is probably onto something. I think the real deal is another doubling in energy density to somewhere between 5x and 10x. E.g. solid state batteries might enable that eventually. It's probably a bit further out. 10-20 years at least. But more than probable.

The impact of this for EVs would not necessarily be cars with bigger ranges but much lighter/cheaper cars with similar ranges as current high end models with faster charging times that only need a third of the battery weight. Anything beyond a few hundred miles of range is basically irrational and overkill. Normal people have a bladder range of about 200-300 miles at best (I get uncomfortable way before that) and ought to stop for longer than five minutes when they relief themselves eventually. Perfect opportunity to top up a battery. But most people don't actually drive that far more than a few times a year; if at all.