I do trust Glazer, just based on what we know of his relationship with Payton, that all of this is stuff Payton has thought about at various times and that they've discussed. So I think Glazer is able to plug that into the current speculation and offer informed guesses.
What Glazer hasn't done is say "I talked to Payton [yesterday, last week, whatever] and he's currently thinking about retiring." (That I'm aware of.) I wish Glazer would have been more definitive when asked but understand he might not be at liberty to do that, or simply doesn't know right now.
So it seems retirement is a possibility but I really hesitate to think Payton wants to go out like this. Of course if he's burned out, he has to do what he thinks is best.
A scenario I could see unfolding is that with three years remaining on his contract, that we could be at the beginnings of an earnest transition plan so that he can make his exit in the next 2-3 seasons. Payton has always come across as somebody who is highly detail driven and doesn't leave things to chance. This organization has been great to him, and him to it. I could see Sean, Mickey, and Gayle working very closely on a succession plan because that just seems to me to be the way they do things.