The part I'm worried about is getting no eeveeloutions and any kind of evolutions from past gens. The main reason behind this is basically the pokemons we already know already got thier evolutions in Gen IV, which was the gen that took part in Japan last. When Gen V is finally announced, it is said by GameFreak that none of the pokemons will include any pre-evolutions or evolutions from Gen I, II, III and IV. Furthermore, Gen V took place in America which was completely new compared to 10 years of regions in Japan. So it is much likely that happened because the pokemons are from far reigons. And now, we are talking about Gen VI which will take place in Europe. So, in this case we might not be encountering with any kinds of pokemon that will be related to past gens and Gen V. Beside from all the things I said, if they would like to add evolutions, why they didn't do it in Gen V. Wouldn't it be unrealistic to make the evolutions come back after a huge period of Gen V?
So all in all:
* Japan is made from first four reigons. And eventually, lots of pokemons recieved both evolutions and pre-evolutions in Gen IV which was the final part in Japan.
* Then we moved to America, which was completely new and we encountered with new pokemons that don't have any single relationship with past gens, from Japan.
* And now we seem like to be in Europe, so what I said above is clearly an evidence why they might not be bringing any single evolution from past gens as Europe is another far away reigon from those.