How would you all feel about letting him go on a free in the summer of 2016 (think that's when his contract runs out). If we refuse all buy offers this summer and he doesn't sign a new contract, we'll still get another season out of him and another crack at champions league (if we make it he might decide to stay), it will give us time to look for a replacement and gives us the luxury of bringing in a couple youngsters rather than a player who needs to make an immediate impact, and at the end we'll be letting a 29 year old go.
It wouldn't be ideal, and I know that Dortmund doing it with Lewandowski has kind of backfired. It would undoubtedly be the best option for Kevin, as its his best chance of getting a dream move to Atletico since they'll never pay a decent transfer fee.
If the best offers for him this summer are around 10 million, I would seriously consider turning them down and making use of him for one more season (who am I kidding, we all know Bill will bite anyone's hand off for 10 million).