What we have seen to date is of course suggestive of what we will see in the future, but we can't know.
I attended an interesting all day seminar on batteries back in the day, 1995 or so, as our company had bought Duracell and they wanted to get suggestions from our group. I remember the challenge of packing energy stably into a small affordable package. It has some apparent inherent limits. You can theorize of course packing more energy in chemically, but stability becomes a problem (and these were not rechargeable). And forget about cost, they wanted a Super AA battery at even triple the current cost.
There were some interesting suggestions from the crowd (none from me). None of them were practicable. Electrochemistry is pretty well worked out, folks in that area know the potential (ha) couples one can envision, and the problems with each. Making it rechargeable is one of the key issues.
Is there a breakthrough out there? Double or triple power density? Maybe, I tend to doubt it. Lower cost and faster recharging? Probably. Better packaging? Almost certainly. I don't know to what extent the current batteries are integrated into the frames, I'm sure it's a lot, but probably suboptimal.