GW they will not allow them in their stores and events. But Legacy armies will get PDF and will be very playable as they have been play tested. I think this is mostly a internal thing with GW's 2 studios and branding maybe? I think most tournaments will allow PDF armies in the events, time will tell.
Whatever the reason I welcome people to play their Legacy armies and 3d print armies to play. If you want to buy GW only stuff that's cool too, I just hope people understand we love rank and file games and Warhammer Fantasy Battle was big part of the fun.