I'd like to see engagements become longer via different shooting mechanics, bullet damage, suppression and newly thought out systems that would all add more depth and make it harder to kill someone.
Squad is relatively slow, but when the action happens it's over very fast. Shorter firefights where few well placed bullets kill anyone at anytime dumb down on the tactical aspect. Where in PR you always need to make a conscious choice of opening fire or waiting, repositioning, coordinating, flanking etc. in Squad you almost always just shoot. If you don't the other guy/ squad might see you and do the same.
This is by far the biggest thing that makes PR INF combat what it is, it favours decision making over being quick on the trigger. It feels more rewarding and more engaging.