So which is it, "1%" or "a third"? The answer is likely well above "a third" especially if you don't have a smartphone (which is the majority of Verizon customers). Also, we a minority of a minority here. I think the Share Everything plans will be a huge shock to people at renewal time and that is why they are not forcing anyone on to one yet. We'll see how long that lasts. And, if they are really getting rid of individual plans for new customers will cost Verizon in the short term.
At a high level, I suppose Verizon doesn't "have" to do anything. However, when Sprint, AT&T and T-Mobile are all offering pre-orders it forces their hand. If they did not allow pre-orders to keep unlimited data, you would see more people buying Galaxy Nexus, Razr Maxx, 4S or just leaving completely.
If you will allow me to don my conspiracy hat for a moment...Verizon had planned to release the S3 in July, after Share Everything came out to induce people off of unlimited data (hence the later ship dates). The other carriers offering pre-orders changed those plans.
Even so, as I said we are a minority of a minority. Only a small percentage of people who will get an S3 on Verizon will end up pre-ordering, the rest will be forced into tiered data. Verizon ran the numbers and decided that allowing a relatively small number of enthusiasts to keep unlimited data by pre-ordering was more desirable than being the only carrier to not allow pre-orders.
Verizon did not go out of their way to do anything. They are a corporation and everything they do is about maximizing profits. Full stop. Verizon is handling this poorly. While we harp about "ship by" dates, for pre-orders they have not announced a real release date.
There is nothing to be thankful for in this situation as far as Verizon is concerned. The only thing I am thankful for is that I was paying attention.