Just trust in 343i, they'll look at what the community wants and well, of course 343 themselves. The ranking system will definitely be different, Halo 4's Ranking System I personally thought was lazy and pointless. Don't get me wrong I loved Halo, but 343 will definitely improve this, especially now that next gen is out, I can't wait to see what they do with Halo 5. I would love Halo 3's Ranking System to make a return but with a new twist, or new look. I would like Social Games and Ranked Games back, I think it's what a lot of people want but all we can do right now is wait and see.
Oh and I don't think the Assault Rifle is at all OP, considering the Battle Rifle and DMR, are the best weapons to use (Long range, medium range and powerful etc), the Assault Rifle needed to be on par, the Assault Rifle is close range as most of us know, so it's not OP.