No need for the SM to "grow up" into a T-bird. The T-Bird already exists.
The SM/BA is not a competent bike for two up touring, yeah I know some of you do, but I see people transporting refrigerators on top of Corollas.
Just because it can be done doesn't mean it should.
That said, I like My Speedmaster (not "love" that's just weird

). And I'd like to keep it when I get a bike for that two up touring; be it a Bird, R-III, or something else.
Even if my wife decides that she may not want to (back issues), I still want something with more ooomph. The R-III roadster would fill that position nicely.
If that happens, I want to keep the SM and do some serious bobbing and murdering on it.