In TV series Legion, NCR & free NV (House or yes Man) are no more. Thus eliminating the events of NV from the future. The TV ending scene shows that NV got nuked, you can see a creator in the credit scene where the Followers of the fallout & Camp Golf is located. The NCR was eliminated by Hank (vault-tec).
the “Battle of the Strip” hasn’t happened yet. The end credits of each episode show what will have happened by the end of the next episode - for example, the seventh episode’s credits show the aftermath of the battle for the observatory, which happens in the eighth episode.
I think he'd be able to defend Vegas with his Securitrons MK2, Lucky 38 defense grid, and further innovations he would've come up with in a year or two
It's probably a 50/50 chance, if house had succeeded in new vegas by the time of fallout 4 or the tv show he would of advanced the wasteland so much past the point of war and squalor and judging by the last shot of new vegas in the show something tells me he did not succeed or maybe he did just not in the way he wanted to.
House is the cannon ending imo, it just makes sense to use the NCR for added Strip protection and raking in more money as well as fighting off the legion raiders who want to seize Vegas and the Dam. All Mr. House has against him is the technology possibly failing but I'm sure with him building his future empire he's bound to have more updated and advanced equipment keeping him alive for decades upon decades. And the courier was initially set on delivering the platinum chip for a price, so House going the extra mile to offer the courier more jobs for power seems realistic and likely.
