The remaining 1100's should be laid up and stored in good order. If
within a year or two, an unforseen problem comes up with the M-7's, the
stored 1100's could with a minimal amount of work be put back into use
at least for a temporary period.
Unforseen problems have come up in the past with a variety of new
equipment and there is always a possibility that problems could strike the
M-7's a year or two down the road too.
If after a year or two or three, the 1100's are not needed, then they could
still be sold whether to a museum operation or for scrap.
Knowing the MTA, this will not happen, they will likely go just like "Dutch"