The specs on PhoneArena (assuming they're accurate) show that it picks up both LTE and 3G signals. Even assuming that specs are wrong, there's no way they would release a phone that only ran on an unfinished, limited data network. I expect the first generation of 4G phones will all be able to tap into 3G as well, at least until the LTE network is more fleshed out.
However, there's a strong possibility that Verizon will require a 4G plan with this phone if it's available in your region, even though it could still use 3G. I'm sure they want to push that network for new customers going forward. Since they've required 3G data plans on phones for a long time now, I can certainly see them requiring a 4G plan for 4G capable phones.