Would he have done it?

[Bergil]

but not by taking the ring. in a desperate situation where Sauron had the ring, gondor, Erebor, Lorien, and just about everywhere else had fallen he would either use his full power or encourage eyeryone (not just elves) to cross the sea to Valinor and explain why when he got there, and prepare for Sauron to attack Valinor (Frodo wondered if Sauron might try this. I think he would), but this is all conjuncture.

[Kuruharan]

there was no guarantee that things were going to turn out well, only a hope. If there were a guarantee that things were going to turn out well, then Gandalf would have known that (having actually met Eru) and Saruman would have never lost hope, because you can't lose what you can't have, and he wouldn't have had hope he'd have had certainty.

I expect that the removal of the knowledge of the "guarantee" would be a necessary part of subjecting the Istari to all the travails of the flesh.

There is no issue here.