I have no crystal ball, so I can't say what the effects of that much oil in the Gulf will have on the diving along the eastern rim. From what I can ascertain, the big hope is that the "domes" they are constructing onshore now to place over the leaks (and siphon off the oil before it gets away). However, I understand while that particular type of technology has been proven effective at shallower depths, it has not been deployed in deep water, so that's an unknown variable at this point. I certainly hope it does work, because it's going to be a long, long time before they are able to get the relief wells drilled, and that much oil will certainly have very significant effects upon the marine environment.
I'm certainly with you in your concerns. I'm scheduled to accompany a science excursion to the Flower Gardens in July. While the blowout is considerably east of the FG, it's not far-fetched to consider that there could be damaging effects upon that pristine environment as well.