Being that DL
just started using the 733s on the BOS
Shuttle (allowing some 738s to return to mailine services), I would think that DL
plans to keep the 733s in the fleet for a while longer.....DL
has also returned the 732s to mailine services (returning from Express services and I believe that some have been reactivated from desert storage) so both the 732 and 733 are likely to see several more years of service. Both the 732s and 733s fleets average about 15 to 20 years of age, and the 737s are very durable, thus, they have a lot of years left on them.
tranferring 36 757s to SONG, with talk of more 757s (or possibly 738s) to be operated by SONG, and SONG opening new routes, the 732s and 733s are needed for the mainline fleet. It is unclear if DL
will, at some point when finances improve, order a direct replacement for the 732 and 733 - it may be that larger next-generation regional jets will take over all services requiring an aircraft with about 100 seats.....time will tell.