I have said before the the heart stones can become a source of great power the way the heart of Lorkhan was for the false gods. I think Bethesda introduced a few new elements into the storry of what is Morrowind so they arent completely irrelivent after losing their home land. The dunmer have a chance at some ancient power and it wouldnt suprise me if we hear about dunmer using the power of heart stones in the next TES games.
You know what it means? Nothing. Bethesda will completely ignore it or just throw one book into the next game saying someone did so and so with the Heartstones and maybe make some speculation about how it is connected to Lorkhan.
Sorry to be a downer, but there are just too many things from Skyrim that could be mentioned in the next game and too many things that probably wouldn't be mentioned in the next game. Most likely due to different geographical locations.
Well the Telvanni could harness the power of the stone, we know dear Neloth is busy investigating and doing his research on them (or was). It could trigger a sort of "revolution", the discovery of a new source of energy the dunmer could use to rebuild Morrowind and strengthen outlying colonies. Thus Bethesda could explain how Morrowind recovered in a short space of time things considered. Or nothing might happen.
But i don't think it's plausible now that i think about it, didn't Azura get mad at Vivec, Almalexia and Sotha Sil for harnessing that same power? If the stones are indeed infused with the power of Lorkhan's heart, wouldn't it be considered heresy trying to harness its power? although the Telvanni wouldn't really care and go "f*** it, that power is ours ".
And if the Tribunal used the Heart as a source for their power, does that mean that Heart Stones could be viewed as a lesser conduit for that same power, possibly extending the use of them beyond their current? Could the power be isolated? Harnessed into necromancy, maybe? Does the Ghostfence have something to do with the ash spawn?
I'd like to see them at least mentioned or implemented in future games.