SPOILERS!!!!
At the end of the Independent vegas ending for Fallout:NV, Yes Man will approach you and discuss how he is going to reprogram himself to be more assertive and that he's going offline. How assertive is going to be exactly? Proof: http://www.youtube.com/watch?v=1Ht8h2fz4r4 18:40
Most of the fallout games had two endings and it was pretty clear that one was evil and one was good so the developers tend to have the good ending be canon. But New Vegas has multiple endings and its hard to say which is the "good" ending (my personal favorite is the aforementioned independence ending). What if this new software that Yes Man installed (regardless of what ending, Yes Man exists and has access to Mr. House's network) made him so assertive that he installed himself as king of New Vegas? If House did die (in most endings) then Yes Man did have full control of the Lucky 38 and the sercuritron army.
I thought it would be pretty funny to see a sequel in New Vegas where the strip is run by a deranged Yes Man who is really nice but has random ramblings of anger and authority (Yes Man Radio?).