While we're still waiting for an official announcement, I'm willing to bet that the SDCC version will just have special packaging and maybe an exlcusive Han in Carbonite. I am pretty sure there will still be a retail version of Boba Fett.
Maybe the only difference will be the colors of his costume. Empire vs Jedi. Time will tell!
Either way, you guys are totally right...Hasbro's SDCC exclsuives are the hardest to get. I didn't even bother with them last year, because even though I'm at SDCC I just don't have the time to wait in 2 lines for several hours just for a chance to get the exclusives.
So I'm definitely holding out hope Fett will also be a retail figure.