Maybe there ought to be a thread devoted to debunking the Paul is Dead myth.
One thing that strikes me is that a lot of people would have to be involved in the overall cover-up. That would include medical personnel, law enforcement, and most importantly, family of Paul. I can't imagine family members participating in something like this for any reason. And think of the grief they'd be feeling without being able to share it with anyone or be open about showing it.
Also, you'd have to pay people off and that would involve a lot of money as well as a presumptive trust in the people you confided his demise to.
I would say this: It probably would be 100% impossible to conceal something like this.