It comes in three parts, one is to continue the evolutionary improvements of the M16, M4 systems. This is in an improved M4A1 that will be getting mass distribution.
Following that will be further evolutions of the system.
The second phase of the M4 improvement program begins this fall and will focus on increasing the M4’s effectiveness and accuracy, with emphasis on the bolt, bolt carrier assembly and the forward rail assembly.
The final part is a potential new weapon including changes to the operating system (direct impingement versus piston).
Interesting stuff, though I suspect they'll merely continue the slow incremental improvement of the system. There seems to be too much inertia given the decades of existing service, with the decades of known performance.