I think so, or damn near close to it. The rate of the legality changes are going to exponentially increase (as they already have). It will especially be the case if the '16 election falls in favor of the Democrats. If not, it may be a little more complicated.
We'll have less than 7-8 states with a ban, surely.
It's extremely likely. If it went to the Supreme Court at this point, they'd probably rule in favor of it seeing how it is happening extremely fast anyways.
It's pretty clear that it will be. Compared to how homosexuality is viewed now to how it was when I was a kid (in the 90s), it's super clear that we will get equal marriage very, very soon. It hardly even makes the news anymore when a new state strikes down their gay marriage bans just because it's so commonplace now.