Hey guys. Remember the Shi from Fallout 2? Those incredibly advanced chinese scientists who created their own city in the middle of San Francisco? They were even more advanced than the brotherhood or enclave, perhaps even the institute. Ever wonder what they're up to by the time of Fallout 3 and New Vegas? I have a theory that can help explain why they don't seem to have been absorbed into the NCR (they would have insane technology otherwise) but also why there doesn't seem to be any conflict between the two groups:

Maybe tensions grew within the NCR and the Shi after Fallout 2. The Shi, being very reclusive and uninterested in wasteland politics, decided to cut themselves off from the NCR instead of fight them, using advanced technology to hide their base away using a forcefield or some sort of transdimensional technology. They continue to do wonderous research within their pocket dimension, and even have contact with members of the Institute on the other side of the continent.

They provide the NCR with energy, just to keep the government complacent and unwilling to attack them. However, the existence of the Shi is an embarassment to the NCR, whose goal is to unite the entirety of the west under one banner. Not to mention how unsettling it is to know that a city of god-tier scientific masters who could wipe you off the planet if you gave them the chance is living in your backyard.

The NCR outnumbers them, perhaps even moreso than they did the Brotherhood. So, the NCR is at least making preparations to strike if they absolutely have to. Their fear of the Shi's technological superiority prevents them from openly declaring war, but in the meantime they need to ween themselves off of their reliance on them. The people of the NCR know about the Shi of course, and are unnerved by them, but they have no idea how dangerous the situation could become, or how screwed they'd all be if, one day, the Shi blast off into space and take their fuel with them.

While this was all happening, the treaty between Mr. House and the NCR had just been signed. Now, they have even less reason to rely on yet another technologically superior force for fuel, and all the more reason to take the dam for themselves.

This theory is obviously just speculation, but I think it fits in with the lore and also helps explain what happened to the Shi between Fallout 2 and New Vegas.

This could all be hinted at in Fallout 4, where hopefully we go to the commonwealth and briefly see a Shi representative talking to Dr. Li before he vanishes into thin air. In Fallout 5, this mysterious plotline comes to a head.

So what do you guys think happened to the Shi? Do you think we'll ever hear from them again? Does my theory make sense?