Yes, Verizon has America's largest network. However, the issue isn't that the Nexus 4 isn't available for Verizon, it is that Verizon refuses to allow a Google "controlled" phone on their network. From what I've seen, I doubt Verizon will get another Nexus device.
It is one of the tradeoffs with any carrier, that you are limited to the phones they allow on their network; though I will admit that an advantage to GSM phones is that most carriers allow you to bring your own phone.