Without coming right out and saying so, the U.S. Army is reorganizing itself like the U.S. Marine Corps did in the 1980s. Back then, the marines turned their divisional and regimental headquarters into administrative operations, and created new organizations to do the actual fighting. The new units were MEUs (Marine Expeditionary Units, actually reinforced infantry battalions), MEBs (Marine Expeditionary Brigades, which were brigades reinforced with support units so they could operate independently) and MEFs (Marine Expeditionary Force), which was a headquarters for controlling MEUs and MEBs. When there was a large operation, the old regiment and divisional designations were used, but the units were basically MEBs controlled by an MEF.
Now the army is doing the same thing. Brigades will officially be called UAs (Units of Action) and the headquarters controlling them will be called a Unit of Employment (UE). The division headquarters will probably be kept as a managerial operation for peacetime training and base administration. The UA will, like the MEB, be given support capabilities (supply and maintenance) to operate independently. Incidentally, this is how divisions were organized when they first appeared two centuries ago. Then, the divisions were basically a tactical headquarters for brigades and regiments brought together for a campaign. It remains to be seen if the UEs will be given the names of famous combat divisions. And many soldiers, and civilians, will continue to call the UAs brigades. Once the army actually has a lot of these new units running around, there will no doubt be more refinements. But the soldiers would do well to look at the experience the marines have already had with this sort of thing. If only because the marines made it work.