The horse has left the barn, the ship has sailed, etc.
While the multiclassing rules were a sore spot for me, they were only one of many.
Even if I were enticed by this announcement to give it another go, most of the guys in my group had their own complaints about the game that I don't think would be addressed in a supplement. A wholesale revision to certain aspects of 4Ed would be required.
For instance, several of the guys in my group are hardcore computer gamers. While they didn't single out any one game, to a man they rejected "marking" as too much like the games they played on their PCs. (And no, they don't frequent boards like this one- they were surprised to find out about the existence of games like Pathfinder, True 20 & Mutants & Masterminds when they rejected 4Ed but still wanted to try an in-print RPG.)
FWIW, I don't play any of the CRPGs, so my "computer gamey" gripe was that the Healing Surges reminded me too much of games like Mortal Kombat or Tekken- games I love but in no way wanted to play at the gaming table.
My final verdict on 4Ed was that it was a good game I'd play (if asked), but I'll never run it.
So, for me, 4Ed is just another FRPG- a well done one, to be sure- but it's not my flavor of D&D, and never will be.