td,
The life of these ac is far from over, especially considering the lifespan/performance. Many operators still fly these ac.
I just flew a UAL MD from DAL to ORF, and the ac was very nicely maintained and really, in pretty good shape.
A few will probably end up flying for some third world operator who can pick them up cheap, then cannibalize a few to keep the others flying for a while.
Air Canada?