Within reason, obviously. If you could find a way to tie an event into the gunner update that made sense and didn't screw up the update, sure, go ahead. I can't think of any way to do that, though. And discounting all gunner gear would probably break the game significantly for a few weeks.
As a way to integrate old events though - you could have different versions of the same gear; functionally identical, but it looks slightly different. So someone who was there for the event can still say "ha, I was there", but other players can stuff get access to the content.
No Draycos, I don't want to play the other side as bad as you think, And yes, I do want a kat hat. But I don't have to whine about it, I will sit here and wait until the event is back and grind like a boss. And also, is two event-tied levels mean that much to you? There are hundreds of different clockwork level out there that you can play while the kats and apocreans are gone. And like the thread I posted at Zeddy, people should really start apprecaite all the good gears OOO has already offered us other that complain about the few that they shelved for a previlidged(hard working) few.