You can't just buy any phone you want. It has to be a Verizon stamped phone because no one makes CDMA phones. The concept of device portability on Verizon is just totally different. So while every new phone thread has someone whining about "Is it coming to Verizon???" that's not really something that GSM users have to worry about.
It's not even about their rules or anything, it's like dealing with proprietary plugs. Sure, I can most likely find a lightning connector just asking a couple of next cube neighbors in my office, but I can't just plug any phone into it. MicroUSB on the other hand is GSM, and what the whole world has been used to. No waiting for a phone to arrive on XYZ network, no worrying about carrier exclusives, etc.
And this whole eventually thing is what I've been hearing pre-LTE. I've been able to get every single Nexus phone to work on AT&T no problems. Look at how many Verizon comments are on the Nexus 5 articles...
I don't want to be a VZ apologist, LOL, but as long as you follow their rules, things go fine. I don't agree with their rules, and don't like them, but you can use their network, and fiddle with stuff, for instance, I put my iPad sim with Data only in my iPhone for a few weeks, and it worked fine, and have put my phone sim in my iPad and it worked fine.
You can swap VZ certified stuff all day every day, and I find used VZ phones tend to be a bit cheaper too, since it's such a restrictive network and the demand seems to be less.
When everyone goes to LTE, all the damn bands will be different, and it's still the same thing, different day
If congress for instance or the FCC would do something, flipping anything that made the playing field even for consumers, I'd just drop dead, as it stands, the regulatory agencies allow the carriers to pull all of this crap.
As far as the N5 and Verizon, we don't know yet, it would be a big deal if Verizon allows it, and IMHO, the ONLY reason they may not allow it is because they won't make a profit on a phone not sold directly by them. The only reason I'm sure that VZ will allow the N7 is that they sell tablets unsubsidized, and charge out the ass for data on them.