I'm sure Chelsea will appeal and have their sentence possibly reduced to one transfer window and maybe a bigger fine. A similar thing happened to Roma a few seasons back over transfer of Philippe Mexes from Auxurre in 2004. Roma appealed and had their sentence reduced to one transfer window. Chelsea have done this so many times though and obviously haven't learnt their lesson so it looks like curtains for Frank Arnesen who was the former Director of Football at Spurs before Chelsea illegally tapped him up on Roman Abromovich's yacht and paid Spurs ?5 million in compensation (hush money) for his services.
It happens at plenty of other Premiership clubs. Arsenal, Man Utd, Spurs, Liverpool you name 'em. Maybe FIFA are actually going to get off their arses and do something about it.