Institutional preference for the M203, usable as an attachment to the rifle rather than use as a stand-alone weapon.
Previousle, it was thought that if a target deserved multiple rounds of 40mm, the squad leader should just have both his bloop gunners fire on it. Serious work in cities recently shows that there's a need for a little more than that.
I hope they don't eliminate the M203s, though, but add the new *sixgun* to the mix. A Marine fire team with two riflemen, [with or w/o M203s] a Squad Automatic Weapon, and a Sixgun would seem to be a very neat way to go.
Alternately, when serious punch is needed, a back-up fire team with a pair of sixguns, two SAWs, and all additional M16 or M4 rifles fitted with M203s....would seem to be a good start.
I wish they would replace the 203 with the H&K version