I am sort of interested in political (and economic) possibilities of the EU joining the Eurasian Economic Union.
This is of course sort of an alternative to Russia joining EU as was asked about in this other question.
The main motivator that I can think of this is that deepening economic ties between EU and Russia would mitigate the risks of outright wars between the two (as in that case they would be destroying their own assets).
Now I am not sure about whether any interest have ever been expressed toward this. On another hand my understanding is that UK's Brexit (if it becomes reality) might make some form of tighter economic integration between EU and Russia more likely.
Excluding lack of expressed intent or interest, what factors (political, structural, economic, etc) would make it unlikely for the European Union to join the Eurasian Economic Union?