He has 2 years left on his contract. Sending him on a year's loan is pretty much like giving him away for free / a pittance at the end of it (similar situation as Suso now though the youngster seems to want to extend and stay now). I think we can keep him around for the first half of the season and further assess in January if we should extend his contract, sell him, or loan him out (which would then most likely lead to an eventual cheap move or free agency departure a season later).
I think a lot might depend on whether Ilori goes on loan again. If he does, then either Coates or Toure will be the 4th CB, assuming Agger leaves. In which case, I'd prefer Coates as he's still young and has room for improvement while Toure is clearly only going to decline. I think January will also be the time when we assess Skrtel's situation and decide if he gets a new contract, as he'll be 30 then and entering the final 18 months of his current contract.
Can only see Ilori going on loan if we can't sell Agger. Either way though, Coates is at the bottom of the pecking order, and badly needs minutes.
I think that trumps a contract situation honestly. We can find the money to extend him next season if we need to, and I'd rather have to deal with that issue than him stagnating as a 4th+ choice option.
Can't see him being of any value unless we loan him out and he can properly develop.