"Then union people would have to fight to get hired back while VZ will pick most experienced - just like in non-union world."
Not quite.
Yes, they could perform a lockout.
No, they wouldn't get to "pick and choose". If they were to lose an ULP charge in front of the NLRB, they would have to bring everyone back. If they won, everyone would stay locked out.
Each of these scenarios opens about a dozen additional cans of worms on legal level and that's why the company hasn't done it so far. Theoretically, they could keep the current workforce out forever without a lockout. Can it be done in the real world? Remains to be seen. Personally, I don't think that we're going to see anything along those lines.