The Arizona Wildcats still have a chance to win the Pac-12, but they would not only have to sweep at home (hardly impossible), it would require a lot of help from Utah and Oregon somehow going 0-3 (who have won their last nine games combined). Arizona is two games back of Oregon and has only a very remote chance to tie for first and pretty much needs everyone ahead of them to lose out.
So that leaves three.
Oregon Ducks: Oregon is in the driver's seat for at least a share of the Pac-12 title. Win their next two on the road against UCLA and USC and they win it outright. Split the series and they will at the very least earn a share of the title. The pressure is only put on Oregon if they get swept, and everything is suddenly taken out of their hands.
Utah Utes: Utah is very close to at least earning a share, but they'll need some help with at least one Oregon loss. The Utes also only have to play one game to close their season, a home date with Colorado. So they have the likeliest path to a share of the crown.
California Golden Bears: Cal's chances are the most remote; the Bears are on the road on the gruesome Arizona road trip, with a do-or-die matchup with Arizona (the loser is obviously out of it). And even though ASU is bad, it's no easy road. Cal also needs Oregon to lose one game; like Arizona, they'd need a lot of help to earn a split.
Here are the current Pac-12 standings.