Umm, no. The heavy users will pay the extra $20 and keep being heavy users since there is nowhere else they can go for the same price service, meanwhile the vast majority of grandfathered in users that I have talked to ( and I was one myself for many a year ) keep the unlimited data "in case of emergency" I.E. their internet at home goes down. Verizon will lose the people who didn't use an excessive amount of data, while STILL having to keep the big users.
It's lose / lose. The customers lose their "safety net" and go somewhere else with cheaper data plans, and Verizon loses loyal customers ( all grandfathered in people have been with Verizon for more than a few years ). Verizon also gets bad PR, and bad word of mouth from the once loyal customers, who previously probably extolled the virtues of VZW.
A happy long term customer is worth a LOT more than a new signed customer. You know the long term customer is going to stay if you keep with the times and don't try to screw them over, you also know they will pay their bills, and probably recommend you to friends and family. VZW should really learn this, the old steady customer is worth a lot more in the long turn than possibly flaky "carrier switching cruisers".