Well, businesses change licence holders periodically. How many companies have had the Star Wars RPG license? I think at least 3 off the top of my head. It's quite possible someone else may pick the this one from GW.
I don't see 40k doing an end times. From what I can see Age of Sigmar didn't do all that well in terms of rejuvenating fantasy, however nice the models are, and I doubt they'll risk a similar financial hit with 40k.