If we are willing to let him go, I think £31m is decent business considering how poor he was last season and how little he offered. It's a bit of profit (we wouldn't have paid £27m upfront and while PSG wont pay £31m upfront, their intiail fee will be higher) and it's a big sum back for a player who has disappointed us. I'm not convinced on him personally and if this £31m can give us a player who can contribute NOW for us, then I'd take it. He showed for long periods last season he wasn't happy either at us or in England, and sulked.
I can see why people see talent in him, I'm just not convinced he'll make it at the top so if we did get a solid offer of £30-35m I'd take it for sure. I get the whole "It's PSG lets raise the price argument" too, but they know we've had a poor outlet from him and can use that, as well as we appear to be dealing with them now with Kean Gana so maybe keeping a positive relationship between the clubs is a good thing for the near/medium future. They may sign someone who is good, doesnt work out there but could be good for us.