What the hell, I'll jump onboard the "I'm not qualified to say at all but here's my prediction" train.
For all the business Transformers did, I can't find a person who actually liked it - certainly not enough to go for a second helping in the form of a sequel.
Terminator 4, Star Trek and Harry Potter will be the big moneymakers this year... in order of least money to most. The T4 people will look at Watchmen's take and use it to justify a PG-13 cut, which will kill the movie's popularity (see T3, Diehard 4, etc.). Star Trek will do alright. HP will be HP, i.e. crazy successful for what it is.