Guess which mod is going to receive a cease and desist order very soon.
Doubtful. Mods for various other IPs are extremely popular, probably one of the biggest sections of the modding community. It falls into the gray area of fair use, so any company trying to incite a legal battle only has its own empty threats and the fear of the modders (or unwillingness to pay for a legal campaign) to get them to stop. If it actually went to court, the aforementioned company would likely end up with egg on their face and a loss on their record. Even if they could get a win, it would be counterproductive due to looking stereotypically evil to their market and everyone willing to work with them as well as wasting time and money on something that doesn't actually affect their copy protection at all; AMC loses no profit from someone making a Walking Dead content pack for Fallout: New Vegas. It would be a 100% fruitless endeavor.
That's why cease and desist orders for modders using other IPs are extremely rare, and I haven't seen any that actually went beyond a company making empty threats and the an ignorant modder panicking and shutting everything down because they don't realize that there's no case that can be brought against them.