COD4 with more attachments, pro perks and killstreaks? That sounds an awful lot like a map pack - which incidently, we already had a taste of with MW2. The best thing about COD4 was its simplicity that made it require a bit of skill. I've seen kids dominate in MW2/3 go ass-up in COD4 because they can't rely on killstreaks and cheap perk/weapon combinations for their kills.
I wouldn't be against seeing some of the WaW maps introduced to MW-style of play.
That said, I think complete remakes would be a waste. There wouldn't be enough interest or financial benefit for the developers like there was with HALO: CE. Because the original HALO couldn't be played on the 360, the remake of that game made sense because it introduced a whole new generation of gamers to the original HALO.
Maybe a few years down the road when you can't play COD4, WaW or MW2 on the XB1140, a remake would be a good investment for the developers.