I'm betting it continues to be a big weekend for Birdman on account of actors playing actors in a movie about acting (not to mention that the ensemble IS truly worthy) but I could be wrong. The temptation to wield your guild's top award as a defacto Best Picture prize -- even though none of the guilds are meant to be awarding that but their own craft instead -- has often proven a strong lure. Boyhood is easier to love so perhaps they'll hand the prize to just four people: Patricia Arquette, Ethan Hawke, Ellar Coltrane and Lorelei Linklater. Otherwise I feel little fear in predicting Keaton, Moore, Arquette and Simmons as the winners. Same as it ever was. That said if Eddie Redmayne is the viable Oscar threat I think he is, things could shift here in Best Actor to put him firmly in first place. After all SAG did go really above and beyond for Theory nominating this three-hander (for all intents and purposes) for the Ensemble prize.
It's worth noting that nominating committees are different than general voting bodies. They are much smaller and more peculiar and they vote much earlier. The conversation about Redmayne's movie has been drowned out recently by discussions about every other Best Picture nominee outside of maybe Whiplash.