From Gamespot:

http://www.gamespot.com/articles/fallout-elder-scrolls-studio-trademarks-void-engine/1100-6416178/

Bethesda parent company Zenimax has filed a trademark application for "Void Engine Powered by Id Tech," suggesting the company has created an all-new game engine. The news comes as the PlayStation 4 and Xbox One are soon to be released, though it is unclear if the new engine is related to the next-generation systems.

More at the link.

Links to filings

http://tsdr.uspto.gov/documentviewer?caseId=sn86113696&docId=APP20131112074110#docIndex=0&page=1

http://tsdr.uspto.gov/documentviewer?caseId=sn86113696&docId=DRW20131112074110#docIndex=1&page=1

http://tsdr.uspto.gov/#caseNumber=86113696&caseType=SERIAL_NO&searchType=statusSearch

Speculate away!

If id Tech can make a game engine with a cellular exterior worldspace system and record-overriding modability, then maybe BGS can ditch the buggy and old Gamebryo-derived stuff they're using...

This means new Doom is on the menu