Please explain how you knew that the NY mob had him killed, assuming he was even killed? Chase hasn't told different stories over the years to indicate "who" did it, even though he could easily put all of this to rest.
Tony was moved back into his house and back to a normal routine, so it wasn't going to be difficult for anyone who wished him harm to follow his movements. It happened with the African Americans that Junior hired early in the series following him to Melfi's office, so it's not that far-fetched for killers without any special skills to follow someone's normal routine.
Or maybe it was like the college visitation episode, where Tony happened to run into a rat that nobody was even actively looking for, and this time the shoe was on the other foot from someone he pissed off?
If people want to buy into every stupid internet rabbit hole theory, then have at it, but don't expect other people to blindly believe it too.