https://www.pcgamer.com/new-vegas-prequel-mod-fallout-new-california-gets-october-release-date/

Fallout: New California is a massive New Vegas mod that's been in development since 2013—and now it finally has a release date. It'll be out on October 23, and will offer a brand new story with 12 endings and 16,000 lines of voiced dialogue. 

You'll be able to sign up to play a beta in July. The main quest, which is essentially a prequel to New Vegas, is complete and the art is finished, but the team are still working on side quests. Apparently there "aren't any" at the moment, so I imagine the finished product is not going to be packed with them. Still, I wouldn't say no to another chunky Fallout main quest.