What Iran Russia China UN USA UK and Saudi Arabia and Co wish to happen is probably about as irrelevant as what we here want to happen.

The only thing that can make any difference would be direct intervention, and that would almost certainly make things even worse. In the same way that the intervention already being carried out by supplying arms is already making things worse.

The assumption that somehow everything would be fine, or would even be significantly changed, if Assad was out of the picture is very much open to question.

It would be great if somehow everything would be sorted out if "we" did the right thing (whoever "we" might be, and whatever "the right thing" is). But it really doesn't seem too likely to be true.