Allow me to stroll down the middle of this road, please:
I think that the SMG will be employed a great deal in the future, as Jeff stated, by special ops units.
I also agree with the premise that the "general military: will not see the SMG, with compatible shorter versions of Battle Rifles available.
I aslo think, however, that we will see (or, perhaps, not see
overall use of the SMG, in taht more and more operations wil be carried out by special ops units in the future. Not just "black" ops, but urban and other "non-conventional" skirmishes will dictate the suse of mroe specialized troops, which are very likely to be armed with SMGs.
That said, I think we will also see a marked increase in the SMGs use in domestic law enforcement. for better or worse.