The more I think about it, the more unlikely it seems to me that he'll leave this summer.
There are only four teams in England that could realistically afford him at circa £50m which must be around the level we'd demand. Man City wouldn't need another player of that type having signed two (De Bruyne and Sterling) for huge money last year. Man Utd have stated that they want four players, they've signed three and are putting all their cash into re-buying Pogba. Arsenal need a striker and central defender and cannot seriously want another midfielder, I simply don't believe those rumours. That leaves Chelsea as the only realistic option and I don't think an attacking midfielder would be my priority there - they need defenders/strikers much more.
So, I've come to the conclusion that he won't move to another English side. With that discounted, who can afford him and who would he want to move to? PSG, Barcelona, Madrid or Munich are the only realistic options. The only one of those that seems practical is Barcelona. Mahrez has said that he's always dreamed of playing for them and if they came calling, we'd be hard pressed to keep him happily.
So, the real question is, are Barcelona likely to spend around £50m to sign an attacking player that will have to earn a place ahead of one of Messi, Suarez and Neymar? The answer is surely no. If one of the other three sides suddenly express an interest, maybe get a bit worried - but can you see any of them doing so? I can't.
Therefore, panic over everyone. He isn't going anywhere until the right option exists for him and us. If one of those three Barcelona forwards were to leave, then we may well lose him. But none seem likely to go anywhere soon. If one of the big four (financially) in England want him next summer, it's a distinct possibility that he'll want to move on if we're not the force we were last season again. But what else could realistically happen?