I suppose that may make sense... but if it is to be the case, I hope the developers put content into the game to acknowledge they are not quite the same species they used to be and the Nords just like to point out how pathetic their former enemies are, hence they pretend otherwise. Only time will tell and I have trouble believing someone at Bethesda wouldn't have seen the things and said "wait a minute... there aren't the Falmer described in previous games", so I do have a hard time believing this is just some oversight. However, we don't really know either way.
i believe it's more like the falmer kept their name as a memento of their grudge towards the nords, a "We shall never forget" kind of thing.
i even had an idea for a quest regarding them
Quest Title - A cold retribution
"a vast and ancient dwemer underground metropolis ruins (albeit mostly intact) now occupied by the falmer, they've been biding their time to retake the surface and now the time is nigh.
even deeper below the ruins, an ancient guardian dwells, the dwemer called it their success of science over magic and in the end the creature turned against its masters and even now it continues to protect the deep ruins...as its property."
the creature (a robotic dragon)
http://i999.photobucket.com/albums/af117/happystreet3/steampunk-dragon.jpg
i imagine it to look a bit like this but more...steampunk-ish, no futuristic planes like in the pic but old style airships
http://fc04.deviantart.net/fs70/f/2011/150/7/4/745fe9ab0018e46e225e0cd5726e3071-d3b9lw3.jpg
i think it would make a great contrast between the surface and the underground
ps: i don't know how intelligent the falmer are but i'd wager they can't reproduce dwemer's technology so we'd see things like armor made out of dwemer spare parts, blades, axes and maces built with pieces of what could have been guns, and the airships are probably dismantled so we'd probably only see pieces of them.