We still issue the M203 with infantry squads, the M-79 is making a comeback and the USMC has a rotary 40mm launcher.
I think it has definite possibility as a dedicated, general-purpose weapon.
However, when it was part of the OICW, it had a 5.56mm rifle in the equation. I wouldn’t want to be an infantry man without a rifle. I suspect they’ll also carry a carbine.
I would too. Only 5 rounds and more operating steps to sight, range lock and fire. Definitely not for rapid fire if your trying to be effective. Bet the rounds are quite a bit more expensive too! $500 per round??