No cells live or die in x generations = end of game.
Anywhere, one after the other.
Anywhere, one after the other.
So cells keep dying and being born forever, yet the game is stable.
You could work out the size of the cycle by checking the lower and upper limit of the populations though, if the lower and upper limits have not changed for a number of cycles it could also be end-of-game.
even then, if the period is very long it might be problematic