Good question - I don't know given the somewhat confusing rumors and articles that came out earlier this year that said the N4 had LTE support then said it was only for a certain band......
Would be incredibly awesome if they could "flip a switch", but I highly doubt that's the case.
Would be awesome if it was an update. The think the reason they had to disable LTE is because they did not submit with the FCC. Maybe they will do that and flip the switch
Otherwise they should maybe let us trade our old nexus 4s in and pay a small amount for a new one.