I believe it originally was a three year contract. But since it's been quite the GP crowd pleaser and has helped the event to grow substantially attendance wise, they've kept it along for longer and will continue to do so until they kill off Daryl.
You're correct. I can't wait for it to premiere. I think that this will be an interesting origin story to watch unfold.
Now as for the rumor of it being part of a dual run TWD house, I'm not sure if that's a good idea. I mean,
what if the show completely flops during the premiere this summer? That would certainly be a waste of part of a house in my opinion when they could have done something else with that space instead.