I have seen in many blogs, some people pushing for "esperanto" language, to be the future language of EU and Europe, even to replace the current nationals...

Well in my opinion, if any language will dominate Europe in the future,it will do it gradualy, naturaly and because people will chose it for the lingua franca...And this language already exists...It is english...I do not see why we need to start teaching a manufactured language to our children from scrap..Even if we do, we must start doing it now, as soon as possible,so it can establish itself with the future generations.

And personally i am 100% against the replacement of our national languages with a manufactured one.My native language is greek,a language that survived for millenia,and i do not see why we should abandon it now...

I am all for though, a second official language in europe.either that is english (that it would make sence,since most of us communicate in english)or other existing european language,french or german most likely...
A second official language that will exist in all member states and will allow even more free movement in people and goods and services...I would love for example to move to Finland,but since i do not speak finnish, i can not,since there is no company there that would employ me without finnish....If there was a second official language,people could move to Czech Republic,Slovenia,Greece,Hungary,Poland,Romania without having to learn the national language in the beggining,but they would be oblidged to do so after they moved and decided to stay for good...They could find employment in all aveliable jobs apart state and goverment jobs, army,police and high ranked executives....Once they learned the native language,they could be employed everywhere...

In that case not only we allow people to move freely in the union without the restriction of a language, but also countries with languages that are spoken widely in the world , notably english and french, due to past colonial history, they won't have to bare with the bulk of immigration into europe,thus causing problems and anti-immigrant feelings. When the language borders will break,then the borders of europe will trully collapse...