Interesting stuff, this. There are other theories that could support consciousness carrying on, even if they're right about the universe ending up in heat death / Big Freeze. Look up Boltzmann brains. The idea is that if the universe remains in existence for eternity then eventually random quantum fluctuations in the vacuum of space will spontaneously create a thinking brain. I don't think many physicists believe in the theory but it does illustrate that eternity is long enough for all sorts of really strange things to possibly start happening, so maybe our current understanding of the universe will cease to apply.
Roger Penrose also came up with a model where (as I understand it) a new universe is born from each heat death, called Conformal cyclic cosmology or CCC.