Its already in the model- 10 quality adjusted years of life. You could reasonable drive that down, but not to less than 3 I'm pretty sure.

I don't think it's appropriate to model current output though. This is a social / political question as much as a economic one. I mostly view retirees as "paid up" members of society and, since I'd like my kids and grandkids to think this way when I'm old be not feeble, believe they should be treated as full members of society.