Transformers@TheMoon, which tracks Hasbro trademarks likely to be Transformers-related, has posted the specifics of a recent Hasbro filing with the US Patent Office. The filing, specified for being related to conventions and related entertainmnent uses, is for the phrase "The Premier Hasbro Fanmily Event." Keep reading for more speculation and info on this filing and details on the trademark itself!
First off, there's "Premier" again, the one without an E at the end and has a meaning more akin to "Top Quality" than "First Appearance." Second, that's not a typo - "Fanmily" seems to be Hasbro's theme for its HasCon activities as TF@TM uses the same spelling repeatedly.
Is it definitely HasCon? No, we can't say 100% for certain yet. But it sure seems like it ought to be, doesn't it?