Energy cannot be created or destroyed, it only changes form, what goes up must come down, all forms of energy have gravity, all forms of propulsion have limits, gravity has no limits.
There is outward pressure caused by the hot dark energy bouncing around like hot air in a balloon, but at some point the dark energy molecules, which are too small to see, will fall into long orbits around black holes and stop pushing against themselves to create the outward pressure.
Then the gravity of these molecules plus the matter and dark matter will cause the collapse, causing another big bang, an endless cycle which never could have had a beginning because no reaction is possible without time, or a previous cause, which must have a previous cause before that. Every action has an equal and opposite reaction.
Everything which can possibly happen happens an infinite amount of times, but there is a limit on the amount of unique things which can happen, due to limited number of different ways a big bang can happen, chaos may not actually be a factor, it could possibly be the same universe each time, unlikely but possible.