Sideswipe was on the leaked Hasbro database, so we could still have Sunstorm, as it was only recently discovered in the American TRU database. Acid Storm and Soundwave were released close together, so maybe Sunstorm will be released with Grimlock.

They didn't show off everything at Toyfair, and they never show off store exclusives unless they have a reason (as it isn't fair to other retailers who aren't allowed to order it), but since the theme this year is Dinosaurs, they showed off the MP Grimlock with all the other Dinosaur toys.
The show is for retailers after all, not fans... so the MP Grimlock on display was not to announce itself as new product, but to act as an incentive to other retailers that this is the year of the Dinosaurs, and that if they want to benefit as much as TRU will (with their Grimlock exclusive), then they had better order more of the other Dinosaur toys to compete.