I can see the advantages to the 13 man Marine Corps squad. Since I think that won't happen in the Army I would at least like to see the Army return to the old 11 man squad of two five man fire teams and the squad leader.

Organize the 11 man squads into big platoons of 50 soldiers: three 11 man rifle squads, one 11 man weapons squad, and two three man command cells. I wouldn't even mind seeing a platoon zeroed out of each company, if necessary, to fill up two big 50 man platoons. How many two up/one back company attacks are we doing these days anyway?

11 men is a bigger than usual weapons squad but I think it makes sense. Base each five man team around a GPMG gunner and his assistant. Now add in a grenadier to cover the gunner's dead space, a sharpshooter/DM (might as well put all the 7.62 weapons in the same squad), and maybe rocket launcher. It would probably be best to have the grenadier be the team leader.

The old 11 man squad isn't as flexible as the Marine Corps three team squad but it's more robust and sustainable than what we have now.