It won't catch on. At least, not as they intended. Most who are in favor of LGBT equality see it for the thinly veiled homophobia that it is. It's getting about as much traction as one of NOM's silly traditional marriage marches, or the "Day of Truth" which was supposed to be some mean-spirited counterpart of the "Day of Silence." You've gotta hand one thing to social media thing, it is a swift reality check of how insular your world is. Even some of my most conservative friends would not get in board with this, so it's easy to forget there are individuals in the United States that virulently hate you enough to pull this kind of stunt.
In the future- hopefully not too far in the future- there will no longer be a need for Pride. A future iteration of it might not even be about gender expression or sexual orientation at all, but merely about free expression of healthy sexuality in general. At such a time, I would not mind at all a celebration of heterosexuality alongside homosexulity, bisexuality, asexuaity, etc, as well as a variety of queer expressions of gender, of which even straight people will benefit since they will no longer feel confined to restrict their expression nor demean femininity from either men or women.
EDIT: When you think about, Pride already is also for straight people. I think it should be for men who want to be Bronies without having to apologize for it. It is for little boys who want to be a princess for Halloween. It should be for women who are tired of being of **** shamed. If a straight guy wanted to bring out his Sailor Moon cosplay to some occasion other than ComicCon, I would be totally for it.