With drums that hold over 100 rounds of 5.56 or 7.62x39, and ultra-high capacity box magazines, I really don't see any purpose to a belt-feed, unless you will be shooting the gun from the prone position. Even if that were the case, I'd much rather someone develop a top-feed alternative.
To me, engineering belt-feeds for small machine guns is as fruitful as engineering scandium handled nylon buggy whips for electric cars.
