I've been thinking about downsizing what I own for several months now. I finally figured out which direction I want to go, in part because cheap .300blk ammo is on the way.
I don't know about "obsolete"....but what I can say is that I'm most likely done buying 5.56 ammo and barrels because for my particular usage, it isn't serving any purpose that another caliber can't do better. I have a bunch of 5.56 stuff, but I don't use it.
I'm in Illinois were rifle deer hunting is not allowed, but there is a work-around with .300blk specifically, in an AR pistol with a follower or sled.
I'm not in rural Illinois, so there are no "long shots"....thus a long(er) barreled weapon isn't all that useful to me. I don't shoot my 20" 5.56...and the lack of long shots (and rifle hunting restrictions) kept me away from the 6.X's.
My original HD gun was a 10.5" 5.56.....I knew that wasn't going to work after the first trip to the range with it. (No cans allowed in Illinois)
So it looks like I will settle on an 8.3" Hanson (BA), and a 10" Performance Series (BA) in .300blk. (Which sucks because I JUST purchased a 9" Performance series barrel).
I'm going to remove the light and pressure switch from my current build (9" barrel, 9" rail)....and swap the 9" barrel with the 8.3" Hanson. This build has a Law folder on it...and will be a true PDW/backpack gun. Short barrel, red dot, sling, folder (and mbus).....light weight, no frills.
New build with be the 10" barrel on a 10.5" rail (and mini-KAK can). Light and pressure switch will go on this weapon. It will not have a folder. This will be the primary HD gun, with the ability to used as hunting pistol (either put on the 3X, or swap on my scope).
I'll keep my favorite 16" 5.56 upper, along with my 12.5" 5.56 upper, but that 16" is really an EOTW rifle. The 12.5" is basically a host for a .22LR conversion kit (which also gives me the option of 2 5.56 uppers for the EOTW).
It isn't that 5.56 is obsolete, it is just not the best round for my most likely usage. Out of an AR platform .22LR and .300blk make more sense. Nothing is cheaper (or more fun) to shoot than .22LR, and .300blk might be the most versatile, and best performing short barrel cartridge available (that will hopefully be really cheap to shoot with Wolf ammo).
YMMV