That proposal seems to be for a 150MHz block. If you try to offer broadband speeds to multiple customers simultaneously with that little spectrum you'll end up needing to use cell sizes so small that it would essentially become a fiber to the curb deployment, at which point you might as well finish off with a handful of ethernet segments instead of several radio links that won't work well.

LTE seems to work well enough with less bandwidth (~60MHz). However I'm not sure what kind of range you can get with 3.5ghz. Surely at least a few city blocks?

LTE works well by the standards of its predecessors, when constrained by draconian data caps and overage charges. It is completely unsuitable as a replacement for wired connections like VDSL and DOCSIS.