I saw one of the Ruger SR556s and it looked ideal for the upgrade. Doing away with the gas venting into the action will get rid of a lot of M4 problems. I wouldn’t change the 30 round mags or the carry load. Everybody knows it’s heavy ... but caseless ammo isn’t real and I don’t think a lighter bullet is viable.
Keeping the ergonomics and shape will retain the advantages found over the years. The SCAR, or variant of same, looks like the perfect solution for the future.
I am glad to see a lot of our entry and room clearing troopers going back to the short barreled riot style shotguns, nothing beats them for surprise parties.