The EU is a myth, it is hard to fight with a myths. It is easy to sell something like this to inexpedient, often idealist people from the former communist countries. There is no reason for us to fight with the wind, they will join anyway. So plan B is necessary, more countries in, better. It will be not the same EU, simply too many groups of interests and the current agenda will be unable to control all these activities.
Well many Europeans in the West already understood, that they are somehow just sucked out by some of their new "partners". Countries who apply for a EU-membership usually know, what it means in advance. If you join a club you have to accept usually the terms of membership in advance. To act destructive after joining in is simply betrayal. Sorry, but that's the plain truth.
Therefore it is quite likely that the Europeans in the East get what they want. A free trade zone and a quite exclusive club in western Europe, that will keep all those countries in "new" Europe out. Probably sooner than later. I.e. there is already a big countermovement in Germany, the UK and France to accept such "banana republics" like Bulgaria or Romania inside the EU (BTW - there is some reason for this stance). They are suitable for such millitary stuff like NATO, but they do not fit into a alliance like the EU. I doubt that the Bundestag (and some other parliaments in other countries) will wave aside their EU-application. There is already a hot discussion about this issue. You will find out that this is just the beginning. It is really quite naive to think that "old" Europe will accept every pool of BS.
Maybe the possibility of a alliance between those countries west of river Neisse and those east of it is also just a myth. Perhaps we should restrict ourselves simply to good neighbourhood without free trade zones, right of domicile or agro-subsidies. Not funny for Polish farmers and plumbers but good for us Germans. Besides - it works perfectly. Germany has a excellent relationsship with Russia without all this EU-crap. We even build pipelines together.