Arguable.
They could still follow you (assuming they hadn't taken a 5' step), but as to whether they can attack afterwards...
Let's say I go to cast a spell (standard action). This triggers your readied action, and you hit me for fifteen points of damage. "I've changed my mind," I say. "Instead of using my standard action to cast a spell, I'm going to whack you with my staff."
Allowable?
I'd say no... and thus, when I go to attack you, and your readied action triggers and you move away, my full round action is already allocated - full attack. I can make use of the 'switch-out' clause of the full attack to give up my remaining attacks for a move action, and follow you... but once I stop moving, that's the end of my round. I don't get to hit you again.
-Hyp.