I'm in essentially the same situation as the OP. I have been a Verizon customer for 20 years, but currently have a flip phone on a pre-paid plan. I wanted to order the X iPhone for Verizon via the pre-order to Apple and pay full price at the time of purchase. In fact, I was just about ready to post this same question on this forum but no need for that now. The answer certainly isn't good news. Really don't want to mess around with changing my existing plan or changing providers until I get a new phone.
Looks like plan B will be to just wait for a few months (year?) until there is adequate supply from Apple.
Even though the pre-order looks as if it won't work out for me, I do have one related question:
On a pre-ordered Verizon phone purchased from Apple, can it be delivered to the Apple Store for pickup? If so, can the Apple Store people get it set up for me on a Verizon post-paid plan or would I need to take it to a Verizon store?
Thanks.