I think he has to go and it could be a win / win,
He gets his desires, we free up a big chunk of wages,
Lets say a replacement costs £15m plus £50k / week over a 4 year deal thats a total of £25m, whereas Jonny would cost £5m / year in wages alone (at £100k/wk).
Also there is no sense keeping a dis-satisfied player IMO, lets be honest the Saido episode proved that. So take the best offer, wishing Jonny all the best and bring in a younger, more motivated player.