If anything happens for the worst then it would be the whole Epic Games being sold to some other groups and that would probably be a disaster for anyone that bought assets on the marketplace, anyone developing anything with UE4 because the new owners then could change everything which means rules, license terms, price or even remove UE4 from the market forever. While most marketplace sellers could easily sell their assets for other engines with only those writing UE4 specific code actually losing most of the work, although algorithms could still be rewritten on other engines even if that means a lot of work.