I don't think that one per man per MGL can provide any meaningful fire for more than a single engagement. Might work for low-intensity with only sporadic fights, not against a conventional enemy. I think that as with a LMG you need two men per MGL.
I view a MGL-heavy section is kind of like a long-range shotgun unit, lotsa bang during the first ten seconds, then 30 sec reloading. And ballistics of the 40mm make hitting further out against moving targets not so easy.

Adding a long-range precision rifle to the squad is a good idea (the Germans had something similar). This would result in a "networked combined arms infantry squad" 1 Squadleader, 5 Riflemen Carbine, 1 Precision Automatic Rifle, 1 SAW, 1 MGL.
I say networked and combined arms because such a setup would have difficulty executing more than one engagement without resupply.

All in all I still hold up my view of a MG for the squad, and all other indirect fire and seldom-used multi-crew served weapons (MGL, RPG) should be grouped at platoon level.
That makes it easier for the

And regarding mini-caliber PDW I think that up to platoon level every single soldier should have a "full" IW. Bulk is not so much a factor when using bullpup rifles. PDWs like MP-7 are not sooo small either.