Fact is that DAL and NWA will need to staff the separate airlines until the SLI is completed. When that occurs it starts a two year clock to combine the operating certificates. It can be done sooner, but I would be very surprised.
I would venture to guess that short or parking 9's and 88 both will probably hire a few. DAL will need a bunch to staff the 777 that are already on the order books.
Now if an SLI is done, all that needs to be done to bring a NWA guy to the DAL side is a BS indoc CD ( Kind of like recall) and a little studying of POH and FOM stuff. If needed and agreed to in the PWA they could take NWA guys and bring there to our side instead of hire. Not that is quite a long shot, but nothing would surprise me these days.