Not so sure about the merge of EVDO and LTE on a handset will too hard.
VZW Global devices already have two radios in them. They could swap the GSM/UMTS radio for the LTE (and associated antennae).
The hard parts will be in the handoff. In theory, the GSM/LTE handoff should be easier. However, VZW's EVDO network is eHRPD which purportedly allows for seamless handoffs between networks.
(if you're bored, read this: 4G Wireless Evolution - Evolution Options from CDMA to LTE: The Benefits of eHRPD
Where they will have issues is trying to have all three technologies in the same phone. I don't see that happening. LTE will be global and I don't think there will be a need for it.