[Even if COH comes back, it's been left light years in the dust with regards to graphics, game dynamics, storyline and overall detail. It will always hold a special place in our hearts, but without a complete overhaul it won't be able to compete.]
Graphics are not that bad... first, a lot of players have computers that couldn't handle the full graphics of the newer games and would have to drop down. Second, CoH has better graphics available if you turn up the graphics, and most likely you would end up meeting in the middle, with new games turned down and CoH graphics turned up, to the point where they are a lot closer than those two pictures.
Game dynamics... CoH is missing some ideas, but it still has excellent dynamics and movement. Some are a bit clunky, but is it really a major deal if the way you jump in and out of mission doors is a bit lame?
A new game could certainly be an improvement, but could also certainly be worse. CoH had a good design and played well, and new stories could easily be added.