I don't see how that could happen.
There's no agency with a reason or authority to ban flavorings, or flavored mixtures of PG and VG. The only component that could be banned, taxed or regulated is the nicotine.
So theoretically, nic could become more difficult or expensive (taxes, licenses, shipping restrictions) to acquire.
Should that happen, then we might see the business change - smaller juice vendors getting pushed out of business or juice vendors selling a blend of everything BUT the nic (if they can't get licensed), etc.