All it takes is one poor season for his value to drop and for offers to dry up. Happened with Klaus, Jaba, Pelkas, Limnios, etc etc etc. It would be logical for them to try to retain him, but if the sums get too ridiculous, then they'd be foolish not to accept it. Personally, I think he plays in a position that is easily to find replacements for.
I do agree that there are a number of players we can get rid of. Augusto, Jaba, Lamprou, Murg, Ninua, Pereira, and Michailidis are all underachieving (though they all have the potential to be pretty good). I like Swiderski and Soares a LOT more than most people here, but if we had the cash to get big upgrades for them, then why not?
Right now, the only players that I think are consistently good in the squad are Krmencik, Zivkovic, Warda, Schwab, Tzolis, Ingason, and Zivkovic. Maybe throw Tsiggaras in there too, at least lately.