So i have been snooping around lately at some of the concept art that was shown during the E3 conference, and I didn't at the time notice it but the very first piece of art seems to be a....zombie redcoat? It appears to be some form of severely mutilated soldier from the 1700's era. I hope that is a enemy because if it is....Then we may just get a musket!!!

Uh-hum, you mean ghoul(JK). Has to be an old fashioned musket in F4, even if it would take ten minutes to reload. I saw a laser musket in one of the clips.

He's definitely some sort of ghoul dressed as a redcoat. Possibly a faction that's against the Commonwealth Minute Men? This is the one you're referring too right?

Spoiler:

I would agree with @Vexillarious about them being a faction, If not i can see them being a enemy that's involved with the MQ but they are also spread around like the enclave in FO3

Looks rather interesting to be honest, however, I don't know how well this would fit in, but this may just be concept art, so we will have to wait and see

Even if it is just concept art and not contained in the final release, nothing an ambitious modder can't fix! Hopefully we'll get to see some Revolutionary themed mods for FO4, that would be really interesting.

I love Revolutionary war history, so hopefully we'll see a ghoul who's trying to be the equivalent of Charles Cornwallis, and maybe a rip-off Securitron version of George Washington. 

I doubt that we'll see a return of revolutionary war style tactics, but I'm not gonna lie, it'd be cool seeing the two go at it in formation with laser muskets, or even with modern guerrilla warfare style fighting. (Depending on which faction outnumbers the other.)