Just to make sure , as long as I have my private keys (even if not wallet.dat) and on Blockchain.info , electrum or anything else .. nothing could go wrong ? and is it true that this Bitcoin XT won't happen before 2016 ?
Exactly. As long as you have all of your private keys you do not need to worry. If Bitcoin XT does happen, it is not going to be before sometime in 2016. However, considering the situation now I do not think that it might happen ever due to lack of consensus. Basically if Blockchain.info, electrum, whatever you're using updates to Bitcoin XT you just import your private keys there and you are good to go.
If you need any more help, you can send me a PM. I would also recommend locking down this thread to avoid unnecessary replies.
You don't need to do anything , nothing will happen