We will know in a few hours, as it was said in yesterday's queue that, IF it will be announced, it will be during the opening ceremony.
I dont think you should be disappointed, as, unless your bf is an employee of Blizz or very close to one of them, close enough to get some insider information, he is just guessing, just like most of us.
However, a lot of people, like the WOW insider staff and other sites, have predicted that a new expansion will be announced, some of them possibly having actual insider information.
Even if not, I doubt they will NOT announce the next expansion... if you look at the last few years, this year is right "in the rhythm" regarding the release-cycle. I highly doubt that it'd be a good idea for Blizz to wait another year with an announcement, and ofc Blizzcon is the perfect opportunity to announce it, so they'd have to wait another year unless they wanna announce it at some trade-show =)
BUT anyway, let's just wait another few hours and we will hear it here, I am sure =)