Ray Allen can still be a productive and efficient Starter for 3-4 more years.
Especially if he is not used in a primary offensive role.
I don't see the benefit of sending Ray to the bench if he can still get it done as a Starter.
I'm not sure if Ray is going to be starter material for much longer. His lateral quickness can't hold out much longer, his explosiveness off the dribble is already way down and his rebounding will continue declining. I think those weaknesses will become increasingly glaring in 30 plus minutes against the opposing team's best players.
That said I don't see his effect on our offense diminishing drastically in the coming years, so I'd love to keep him, just not at a price that keeps from adding a starting quality wing (Mike Miller) to help make-up for some of his decline and maybe transition him to a bench role.