I was just thinking, everyone says the universe will one day just and and be dead, but why do black holes keep gathering mass and energy then, I mean, all matter is just energy in it`s purest form and since black holes gathers mass over time and get`s heavier and heavier, will the weight eventually be so much that the mass breaks down to energy again and become a new sun? It`s a kinda strange idea that the universe will just be dead in the future when it came from nothing and, like, why can`t it do it again also? I know the inner fire in our own planet won`t last forever, and therefore the electromagnetic field around it will die also and all life, but one can speculate a little also that since we`re moving very fast through the empty space, that sooner or later it`ll end up near another sun again and go into orbit around it, but I guess it doesn`t matter so much if there`s no electromagnetic field around it, I don`t know, perhaps get surprised anyways?

Nothing can escape the event horizon of a black hole, not even light.    Mass and energy both contribute to gravity.  So its not as if "mass breaking down into energy" would decrease the gravitational field of the black hole or cause its event horizon to cease to exist.