did he expect us to put a placeholder in until his return? 

I never expected him to play next year, at least not play and make any sort of difference on the season because of the reasons some have said elsewhere, it wasn't likely he'd get any significant snaps in practice because the QB's who are here and playing will need all of them.  To expect him to come in mid way through the season under those conditions and do anything is totally unrealistic.  Even if he did come back and start, it isn't likely he would have played with any rhythm until late in the season.

To be honest, I'm not too sad to see him go.  I don't have a lot of faith that a guy who'd make such a disastrous decision for himself and his team like he did this year can be trusted not to do something else again.  There are mistakes and then there are MISTAKES.  I don't know about you, I held my breath each week this season with Treon, hoping he too wouldn't do something that would disqualify himself for the rest of the season.  I think it best for everyone we all start over fresh.  If that means next seasons expectations need to be adjusted, so be it, that is the price of the decision Grier made earlier this season and one we all have to live with.