@afriendofours that's a very popular theory on what happened. It is one me and all of my friends have come to terms with.
It is my understanding that Patsy set Tony up to be killed. If you rewatch the series with this mindset, consider every time Patsy is on screen and it almost jumps out at you. Whether or not Patsy, Tony, everyone or nobody gets ratted on by Carlo they were all involved in the same indictable crimes, and with Tony involved by Carlo's ratting anything would fall under RICO so Patsy would go away too if Tony did. I feel Patsy had Tony killed and this to me is how the show ended.

PM me if more explanation is needed I can go into detail, again it's just fan theory this IS NOT be saying I definitively know how the show did or didn't end, I simply have a supported theory my friends and I have worked out.