If Mongoose were to take over the MC Warzone / Chronopia titles I'd recommend the following.
1) The Warzone name has developed a stigma, from the last 2 bearers of that name. I'd recommend going about the same approach Urban Mammoth did with Void 1.1, by remarketing everything under the Urban War name. Urban War, a skirmish version of the Void 1.1 game, seems to be taking off quite well and even the UM folks recognized sales improved on Void models when they relabled them under the Urban War name. Also, a new version of Void 1.1 will be coming out this year under the name Metropolis (keeping with the Urban War name). First I'd work on renaming the game, something different yet recognizable. I'd recommend "Mutant Chonicles: Miniature Wargaming in a Universe Under Siege". The MC name has not really been used in a long time, yet would be easily recognizable by it's fanbase. Also it should tie in with the upcoming movie.
2) Take the existing Ultimate Warzone rules and just clean it up and edit it! It's an excellent rules set, just poorly executed. Biggest complaint amongst even the biggest diehard fans. Perhaps break the book up into 3 books like Warzone 2nd Edition, Core Rules, Fluff Text, and Army lists. BTW, those rules (both Ultimate Warzone & Chronopia 2nd Edition) would also make good skirmish-level rules for other Mongoose titles like Babylon 5, Conan, The Wars, Lone Wolf, etc.
3) Clean up the miniatures catalog. Start with filling in miniatures that don't exist yet. Drop the really ugly, poor sculpts and replace them with new. Some troop-types can be doubled up with perhaps 1-2 model replacements or mods. For example, the original Brotherhood Troopers (very poor sculpts) were replaced with much better sculpts, and then were renamed Elite Brotherhood Troopers. Drop the old sculpts, use the new Brotherhood Troopers as both Brotherhood Troopers and Elite Brotherhood Troopers (just suggest painting them differently) and release a new Elite Brotherhood Trooper Sergeant (which could be as easy as modifying the existing new Trooper Sergeant by replacing her Punisher Pistol with a Machine Pistol). There are lots of other cases where this could be applied.
4) Start producing small campaign packs full of scenarios and fluff. Something quick to put out would go a long way to support the game while longer leadtime items (like 1-3 mentioned above) are taking place.
5) Support the game. Mongoose already does an excellent job getting the name out there and supporting it, from this forum, to convention support, to S&P magazine. This was one thing that people really complained about with EE, but Mongoose seems to do rather well.
6) Start making an OGL based RPG for both MC Warzone and Chronopia. Both titles have very rich backgrounds and artwork that would make a good rpg setting. Plus tons of models that already exist.