Based solely on the fact that Friday contains considerably less artists than the other two days, I would not be surprised to see The Police added to Coachella yet. Further, I think that it will be similar to Madonna last year, where there will be very limited competition in their time slot. It was far less than ideal, but GV proved that they could get away with it.
I think that the announcement will come after their Grammy appearance next month, which would make sense (don't want to steal thunder from their first performance in 20 years). I could be wrong, but until Friday fills up, it's possible. Does anyone agree, disagree?