Total nonsense. Verizon doesn't mess with their smartphones. And they turned down Apple mostly because of the extra money they wanted, lack of warranty control, and a disagreement over what stores it would be sold in.
As for crippling, Apple is the one who took the iPhone and left out Bluetooth stacks, no MMS, no themes, locked it down to one app store, etc.
Verizon has their FiOS network, plus they bought MCI for their fiber backbones. So yes, they can expand their tower backhaul (and are doing so) far easier than other carriers.
Then stay away from the ATT iPhone, since they've removed the ability to use local SIMs overseas.
LTE's air interface is not backward compatible with anything. It's something new. Phone makers would have to build in fallback radios for either GSM or CDMA.
As others have pointed out, there's no standard yet. When there is one, Verizon (as a major first LTE adopter) will probably decide what it is.
In any case, Verizon sees LTE more as wireless FiOS. That is to say, as a wireless broadband line for laptops, cameras, gameboxes, etc... not necessarily as a phone network. At least, not for years to come.
go read some howardforums. AT&T is supporting several old technologies on it's cell network and they have to support them. they can't just add towers anywhere either since you first have to lease the land, get permission to dig and run network lines to your towers, provision electricity, etc. you're probably talking at least a year of work per tower