Its way too early for a reboot. You just brought back the OT for an X-3 sequel. The OT is still very fresh in peoples minds. If they continue to ignore that continuity, and the OT merely serves as a backdrop for movies going forward, then I am going to consider FC as the reboot. It could then be perceived that perhaps some variation of the OT existed in the old timeline, but certain characters/events are to be ignored entirely, and this can be a very pernicious thing to the unilateral universe Fox is trying to build up. If they continue to muck up the continuity in the franchise with respect to character ages and events that should or can no longer occur (irrespective of changes directly or indirectly resulting from the time travel to 1973), then its obvious the franchise has already been rebooted.
For me, 1983 is not the place to see the original X-Men. The characters should be children. Teenagers at most. If Angel shows up, then I really dont know what to think. Seems like they preserved Kitty from TLS, but other characters that were perfectly salvageable from the OT will now be ignored. It really becomes a slippery slope at this point. Obviously there are ways to get around the ages of certain characters and events from a comic book movie standpoint, but I cant view the OT as being of any relevance, whether one wants to hold onto them or not. But the opportunity is there, right now, to completely shed the OT and complete "the reboot", by providing us with events and characters that completely contradict Singers original films, if that's what Fox really wants. Can't say I'd blame them if they went that route.