I don't think that the Bills plan on keeping Peters at RT beyond this season.
Just because he haven't heard about it doesn't mean they're not working on an extension with Gandy. The problem is, and this is the reason I think he'll be gone next year, is he now sees himself as a non-sucky LT, and knowing what LT's make, will want LT money even though he'd probably be better served at RT and at least OG. I doubt the Bills are offering much and if he wants too much to re-sign, he'll be gone.