Yeah the warmaster loss sucks and not to make light of the loss but at least pendragon and other lines have excellent 10mm compatible products. Fantasy is a very safe product range from IP lawyering as frankly you can't really enforce it outside of naming and some very specific symbols. I am not sure if you are a member of the sister site, Specialist-Arms but there's a pretty good
catalog forum over there that could be a great benefit to you.
For Epic players there's a more diverse situation for them.
-Guard/Traitor Guard-Blood Pact style armies are really safe as the defacto 6mm Sci Fi army is pretty much compatible right off the bat. There's some losses with say a Leman Russ but very very nice identifiable proxies from Spartan Games and EW and DRM all fit in really well. There's plenty of WW1 models out there that fit as too and let's be honest, the damn thing is a straight up gaffle of a vintage Mark VII design anyways.
-A pure deamon army is a tiny bit harder but frankly those designs are all pulling from standard western mythology and archetypes and art work ( see Hieronymus Bosch and that's 99% of the starting point for GW's Chaos interpretation). Much of the need for identifiable proxies is handled in basic painting (Red vs Purple vs Green vs Blue) and some minor modeling.
-Squats have already been in the situation they're in for years now so no real change for them. Space Dwarves are frankly not an IP enforceable concept anyways and I expect to see more stuff from EW in the Khazari range and I'm sure more will come (Looks at deacon
).
-Dark Eldar have always been a DIY story though bootstrapped from Eldar lines. I expect though that the new stuff in the pipeline from Onslaught will help out that tip.
-Orks. Well they're basically just like any "[insert fantasy creature] in space" and TOTALLY not IP enforceable. You probably can't / shouldnt call them Orks but you can call them SciFi Orcs (using the classical English spelling from folklore), Green skins, Green Aliens, or whatever. Considering how ramshackle and off custom and off the wall all their kit really is just about any model line and manufacturer really works for them. Weirder more GW specific items are really easy to kitbash (Gargants for instance).
-Ad Mech. Well they've never really actually ever had a line other than Knights and those are actually pretty easy to proxy from any number of lines. They have a pretty baroque feel to them so the Spartan Games line is perfectly suited for them. TMG, EW, and DRM already have great 6mm infantry available or in the works.
-Tyranids have been OOP for ages. I'm seeing fantastic proxies from Onslaught's Legion line. Frankly they're my next army.
-Necrons are another kitbash and DIY dream. Egyptian style stuff is easy to come by. Their vehicles are really more like floating SciFi Egyptian Temples and Tombs anyways and easy to build. Exodus wars Edenites look spot on for 'Cron infantry.
The real hurt comes to CW Eldar/Marines (traitor and loyalist) as they're the most difficult to sidestep IP issues while looking like Eldar/Marines still. For a while Ebay will help as they're the two of the three largest and most popular lines so large stockpiles of stuff exists. However that's ultimately unsustainable situation. I don't know what the future holds for those armies.
BFG has an interesting situation. There's great discussion going on
hereI don't know much about Blood Bowl but again, fantasy creatures + rugby/football isn't IP enforceable and as I understand it there's already a plethora of alternative lines that are available.
I've never played Inquisitor or Mordheim or Necromunda but size issues aside, GW 40k/WHFB are not going anywhere and are can used easily I expect. I also hear from various boards that lots of players are leveraging Infinity and other lines today already.