As far as I'm aware, elliptical galaxies form when a galaxy collision randomises the momentum of stars so they form an elliptical cloud, a momentum which stars keep as they experience virtually no friction; but what about the gases?

Obviously the gases must flatten into a disc in a reasonable timeframe, and depending on how the spin of the galaxies was aligned at the time of collision this disc could have very low rotational energy (thus a very small radius).
So what are the implications of this? Does this mean that near-spherical galaxies can shrink to miniscule sizes as their gas loses energy, until eventually it's just an extremely dense cluster of stars with the only far-out objects being red dwarves and stellar remnants? Do any galaxies like this exist?