Not to be the negative Nancy of the bunch, but why? It's a niche round that currently only exists in a platform unavailable to the extreme majority of gun owners. It seems to be a round developed for a very specific purpose and really only shines with burst fire. There may be a few out there would want to get one if HK crammed 22 rounds in the grip, but knowing HK they would limit it to 15.
If they released an MP7 civie platform along with a VP4.6 it may sell a little, but as a stand alone I really don't think they'd realize much return on investment here.