Mark already specified at least 3 times in the last 2 days they aren't going to. Technically it can't mean never since the game may be around for 10 more years, but it's kind of unrealistic to think of as possible design space.
Plus, PWs are characters and are special/unique. There's not really any reason to make non-legend walkers. It's as likely as making a legendary creature that's not supposed to be a 1-of and nameless.
edit: "It won't happen until maybe it does happen" - this doesn't seem to mean anything? That's true of everything if we are getting really technical. I can't begin to see how that's even a reason to believe that it will happen, much less makes it 'likely'.
