Simon, thanks for giving the accurate numbers and those helpful links.
I have edited my post to reflect the correct numbers (using raw GDP.)
I'll admit that saying never is going too far, so i'll take that back.
When i said that the expansion of the EU to the east will have to stop to the border of the former USSR, i really meant it as "for the foreseeable future".
The EU has to expand to the east progressively and in logical steps.
The first step is Central Europe states + Baltic states.
The second step will be eastern Balkan states.
The third step will be western Balkan states.
Between each of those steps the EU will have to take breaks of several years, integrating 15 countries that are considerably behind in terms of economic development is not an easy task. The goal is to bring every country to the level of the older 15 members, not to bring every one down. As rich as the older 15 are, there is a limit to how many countries they can help at once. Things have to be done progressively.
So in my opinion, anything further east than the former USSR border will have to wait for the foreseeable future, especially since those countries are members of the CIS and are receiving help from Russia.
I'm optimistic though, i'll say that it's going to take from 10 to 20 years for the former communist countries of Central Europe and the Balkans to fill the gap with the older 15 EU member states. That's not that long.
And Ukraine may not still want to join the EU in 20 years, they may feel more comfortable within the CIS with Russia.
In any case, the debate on the future definitive borders of the EU is interesting. It is time for the EU to make a final list of which countries will be allowed to join and which won't. The EU citizens need to get a clear picture of the final shape of the EU, to reach a stable political Union the EU need fixed borders.
Personally, i stay on the list of 10 more countries i've given in a previous post. That would be an EU with 35 countries covering an area that i consider suitable to develop a wealthy economic union and a stable political union.
A brief article on this topic:
http://www.euobserver.com/?sid=15&aid=16346