What if Gollum had repented?

[thorondil]

I agree...the only thing that kept him alive was the ring, and after he lost it (or rather, it lost him) his desire for it. Gollum repenting...even if he did, think how long he would be in Mandos.

Even the Noldor:

There long shall ye abide and yearn for your bodies, and find little pity though all whom ye have slain should entreat for you.