If GB leaves EU will I need a new passport right away

[NotAllThere]

Going to Europe in Sept 16, current GB passport clearly says "European Union" at top, will this passport need to be replaced before travelling if there is a BREXIT ?

Can't find any mention of this possibility anywhere.

In: You'll have to replace your passport and you'll be subject to intimate rubber glove searches everytime you cross the borders.

Out: it won't be a problem, but as a patriot you'll want to replace your scummy EU passport with a noble British leather-bound document.