I think so to. The treaties are after all between states. So far the EU consists territorially only of the member states territories, it does not hold any own territory. So if a new state wants entrance it does not matter (legally) if its territory has been part of the EU previously.
Of course, this makes it really interesting if you have break down of a state without any clear successor state. A vote for PES is a vote for EPP! A vote for EPP is a vote for PES! Support the coalition, vote EPP-PES in 2009!