While we don’t know what Warner will be working on at Visceral, it is thought that he is working on a yet to be announced Star Wars title that is targeted for the next gen consoles. The studio is said to be working on this new Star Wars title while they are taking a break from the Dead Space franchise. (Not surprising, really, considering the last Dead Space title was not all that and a bag of chips!)
It is difficult to say what this could mean for Halo 5, which fans know is already in development after 343 and after Microsoft teased it for the Xbox One at E3. Details on Halo 5 have been very few, but it is thought that the title will be part of what is now known as the Reclaimer Sega. It is unknown what role Warner might have had in working on Halo 5.
See Warner’s announcement here.