Reading up on Trademarks Bethesda need to continuosly use the Trademark in order for it to not run out. This article was clarifying: https://www.legalzoom.com/articles/how-long-does-a-trademark-last
You know that somehow companies and corporations manage to extend copyrights again, right? Anyway I will be long dead so why should it matter for me. Or civilization probably has gone into collapse and we play Fallout for real.
This article was clarifying: https://www.legalzoom.com/articles/how-long-does-a-trademark-last