IMO there's a risk of upsetting the Chrome monopoly and driving users away if they do it in such a heavy handed way.
Also, they would either have to completely neuter their Extensions, or else constantly battle people submitting new adblockers in the same spirit as uBlock.
But if every browser slowly adopts Chromium engine (the worrying trend), then they can make a move against adblockers and competing browsers would have to scramble to remake a competing browser engine to do anything about it.
