BB15 will air most likely. As has been pointed out by others, why would such a great effort to change the show for the better (such as Emma, completely new house layout, AJ & Rylan + Live Feed) if they know they are going to cancel it at the end of this year??
You don't need to have seen the contract to know that Big Brother is profitable for a broadcaster if it airs for 13 weeks in the summer (as with the C4 days) Ergo, There must be a civilian BB every summer or it wont generate the advertising revenues it needs.
C5 decided to shorten it's regular series to 9-10 weeks to allow for a summer CBB, still the same principle. Luke A is probably in all honesty just being pessimistic.
On the other hand, I can't wait for Launch night on Thursday, Bring it on!