There's no proof the universe will end in a Big Crunch. Apparently there's some measure of the universe where if it's less than 1, we'll get a Big Crunch, and if it's greater than 1, we'll get a Big Rip where everything just falls apart. I may have those backwards, but the important thing is when it's exactly 1, it implies a universe that continues forever, getting colder and colder. And as best as science can determine for our universe, the value is precisely that.

But here's another, well, dimension to that: There's a popular but unprovable conjecture that our universe is the inside of a black hole that exists in a higher-level universe. In our universe, black holes boil away due to Hawking radiation, a process that can take trillions of years for very large black holes.

Once the black hole we're inside of stops consuming matter in the level above, that spells a very slow but alternative end to our universe. One day it will simply cease to exist.

"This the way the world ends: Not with a bang, but a whimper." -- T.S.Eliot.

Sometimes I think our universe is just an explosion in a big ass combustion engine.

So everytime I drive a car I create and destroy countless universes just to get some nuggets. Worth it.

Somehow I find the Big Crunch more comforting than Big Rip...

At some point, it will slow down, and then stop

All of the current scientific evidence disagrees with this. 1) There is a velocity such that you can go faster than gravity will be able to slow you down: escape velocity. So, it's possible even without any new, weird physics. 2) The hubble constant shows that the universe isn't slowing down, but the opposite: it's accelerating. Physics doesn't know why (see Dark Energy). It's physically measurable that things farther away are accelerating even faster scaling with distance.