Heat death must be viewed through the lens of entropy. Assuming no big crunch and no big rip, the "heat death" represents the end of any information-containing computation. It doesn't mean that physics ends or the universe literally freezes into place with no motion anywhere; things can still encounter other things and interact, even if the rate of such interaction occurs across time frames currently inconceivable. But it has no information in it, which means that there is also no "meaning" by any human definition of the term.
If things can interact, how can we be sure that there is no information being passed around in it? Information processors might still arise, just computing over timescales unimaginable to us.
By comparison, you might have information processors existing in the first second of the universe, celebrating for subjective aeons their low entropy compared to the frozen state that would exist fourteen billion years later.
Not terribly relevant is my understanding. Heat death happens when everything is far colder and more spread apart, mostly turned into leftover radiation.
The article mentioned that scientists made predictions about these reactions, but they still predicted heat death, too.
Both the "heat" and "death" part of heat death are a bit of a misnomer: it's not so much about things being so cold as to be dead, and it's definitely not about being spread out so much no interactions happen anymore: it's purely about the universe being in state of thermodynamic equilibrium, where interactions can still happen but do not increase entropy. In theory, the entire universe could be a million kelvin plasma, but once it reaches universal thermodynamic equilibrium, that's its "heat death".
I always thought interstellar space is an inert medium. But it seems something “interesting” _can_ still happen.