Warren Ellis has confirmed that the third and fourth announced WildStorm titles - Wildc.a.t.s. and Zealot - are still in development. Originally announced back in October 2016, these would follow the current The Wild Storm and Michael Cray limited series.
"The other planned Wild Storm group titles are still coming out," Ellis wrote in his newsletter. "Scheduling is a real thing in the world, especially at a big publisher. The third book is outlined and already has a script written, and the bible for the fourth is in my files and being refined."