1.The Big Crunch- a state in which Dark Matter(which creates gravity) prevails over Dark Energy(which creates a kind of antigravity)and all the matter in the Universe comes together at the singularity from which it all came form and colapses in on itself.
2.The Big Rip- The exact opposite of the Big Crunch, Dark Energy Prevails over Dark Matter, the antigravitation is so great that even the fabric of space and time will tear apart.
3.Steady State- The amount of Dark Matter and Dark Energy are equal. The Universe will continue expand and will eventually stop.
4.The Big Chill 1- Dark Energy is slightly more powerful than Dark Matter. The Universe will continue to expand until there is no matter left.
5. The Big Chill 2- The Universe will keep expanding. The expansion will slow down, but never stop.
I think it makes rational sense to consider the universe closed, but you are right - the evidence points towards an open universe; mathematically it makes more sense anyway. The current models of the universe have it drawn as a rough sphere, so I don't know what the future shape will hold. If our rate of expansion and the dark energy that seems to be hurling us away from every other galaxy then I don't see how it could retain this spherical shape. But I don't know enough about the entropic premises to understand the conclusions.
Rationally it makes more sense because we, as humans, try and force ourselves to believe what sounds better to us. Case in point: There are still people who deny global warming. But the open universe makes sense, when you think about it.
