Bit puzzled by the comment "I have heard from a reliable source that of the approx 50 low cost airlines that by the end of this year only the big 4 will be left"
This is an opinion not information, so it is more prediction skills than reliability I would look for in ascertaining the credibility of such sources.
I think 50 to 4 within 7 months is a bit (nay, a lot) of an extreme prediction - but I would definitely expect to see a few disappear. This has been covered on other threads