The Bunnies always spend a lot of time with Forge World and Black Library at these events, often neglecting to talk to the GW and Citadel staff. The reason why is, they never answer any of our questions and are not allowed to share information regarding future releases.
The tides may be changing now. Apparently some person who spoke to the plastic designers has revealed that there might be a plastic Warhound Titan in the future (we already know they are capable given the Aquila Strongpoint).
So if this is truly the case, then we are extremely fortunate and it would just also add further stock to a plastic Thunderhawk too. Given that the Sokar is finally out and the Thunderhawk is the FW model that seems to make it onto the pages of WD almost every other week; I once again say it is just a matter of time before we see a Plastic Lucius and Plastic Thunderhawk.
Other Titan designs are getting talked about again.
Another mid class Titan (between Reaver and Warhound) will be considered next.
Nemesis possibly will be the biggest Titan they do (will be Warlord based but with bigger guns / mounts).
The superbly talented Darren Parwood is working on something else big now. I believe this may be a light Battle Titan. We may not see it for a while though.