It's probably unlikely Hurt will be the "real" Ninth Doctor purely for pragmatic reasons - it would instantly render all Ninth Doctor merchandise incorrectly labelled. In this case, even if Moffat wanted to do it, the Brand would prevent him from doing so.
Worldwide doesn't have that kind of veto power.
I agree it would cause merchandising problems, but I don't think they would be insurmountable, especially if BBC Worldwide gave guidance to their licensees so that they're all on the same page.
And I'm not sure how big a problem it would be. How much brand new tenth Doctor merchandise is on the market that says "Tenth Doctor" on the package?
I actually think it would be Doctor Who Magazine
that would have the hardest time. They would either adjust or they would put their head in the sand like an ostrich. (Personally, I think the latter is most likely; DWM
uses an entirely different series nomenclature from everyone else in the world.)