Dream or not, but it is foolish to assume that current borders are set in stone and will not change forever from now on.
Soviet Union also was called "союз нерушимий" and not many people in, for example, 1985 thought that after ~5 years it will not exist anymore.


And for me it is more believable that parts of Russia joins EU than Russia in its current state with its heavy corruption, authoritarianism and беспредел.