Am I misremembering that LCT generally doesn't announce a full season of shows? I don't have time to comb back through old press releases right now, but my memory is that they tend to announce things piecemeal, for all 3 of their spaces. They're not selling season subscriptions in the same way other theaters are, so they don't have to package/announce their programming that way.
In this case, they had been selling Camelot through Labor Day before they announced the early closure, and they probably hoped to extend it even longer the way they have with some of their other big musicals. So it makes sense that they wouldn't have anything queued up for this coming fall.