@ LTE phones/bands

I've been reading about different spectrum bands that phones and carriers are currently using and plan to use in the future and I have a question.

The current set of lte phones... those are only designed to work on limited bands for lte correct? For example, if Verizons lte phones use bands in the 700 MHz range, then if they open up something in the 1600 MHz range for lte down the line, those earlier lte phones will not able to lock onto those access bands correct?

If that is so, lte phones will get better with time since phones released in 2-3 years will presumably be designed to work on newer lte spectrum channels.. correct?