Thinking about this thread has raised a different question; do we need pistols at all? While employed in the D&S platoon in Banja Luka, I wore a pistol on duty as a symbol of my rank and authority, but I was convinced by my troops that the pistol would be better employed on the actual gate, since it could be brought into action at close quarters (when next to a car) far more quickly than a rifle. This being said, a pistol has only limited effectiveness in this situation, since most of the bullet's energy would be expended in penetrating the car. (The "powers that be" did not agree with the reasoning).
So, what is the pistol for? Is it to indicate rank and authority? This could be done with a brassard or a different hat, and has the disadvantage of marking an individual as different, which would lead an enemy to target that person. Is the pistol for CQB and personal protection? In that case, it is of only marginal effectiveness (please, no .45 ACP vs 9mm replies) mostly due to the ergonomic issues (i.e. holding, aiming and firing).
If we are to agree that a pistol is the current thing for CQB and personal protection, then we can look to discarding the pistol in favor of a weapon that is compact, has a lot of firepower, and is fairly easy to use. If we don't want to change the supply system, then a C-8 with the stock collapsed would be ideal, since everything from ammunition to training stays the same. Next in line would be conventional SMG's like the HK MP-5 family. If we want to play around with terminal effects, then a militarized 12 gage shotgun is in order. Exotic weapons like the PW-90 or Metalstorm can be considered, since they offer a of of features which other weapons do not, but the changes to the supply system also have to be considered as well. Is the advantage great enough to offset the addition of special ammunition natures?
Historical analogies would suggest the answer right now is NO. The Enfield EM-2 pioneered the western use of "assault rifles" in the 1950s with the ".280 Ideal" cartridge, but since America was organizing and QMing NATO with millions of surplus .380 Winchester (7.62 X 51) rounds, the .280 fell by the wayside. Similarly, there is a consensus the ideal LMG round is actually 6.5 X 45, but we don't see too many of those, it is more practical for the section weapons to share the same ammo.