Carbine/hangun combinations have been around since the advent of useful centerfire cartridges (i.e 1873). In the later Old West the 44-40 and 38-40 et. al. appeared in both the Colt SAA and the Winchester 1873.
You can still own a revolver and carbine combination and enjoy all the associated advantages.
It's harder with semi-autos and only Beretta has a current model line that includes pistol carbines that use the same magazines as the pistol.
I think Springfield could fix that with an XD carbine.
It would give them unparalleled breadth in their product line: everything from subcompacts for CCW through full-sized service pistols and a long gun that uses the same magazines.
