This is obviously all pure speculation so it becomes impossible to say and therefore the likeliest assumptions will be made based on each individual's own bias. In other words, if you're a fan of Gotti then you probably assume the most favourable outcome for Gotti.
That's not to dismiss your assumption: I'd be inclined to agree that Gotti would have an obsession with getting to Gravano for as long as he's around. With that being said, he was around for a whole decade and nothing happened to Sammy. And all these years later when Gravano is presumably an easier target, I'd have to say that even if Gotti were still alive he'd be virtually irrelevant to the Gambino family today and I can't realistically see a group of fairly sophisticated guys like Mannino actually deploying resources against an old grievance, which, if successful will guarantee heat on a scale they haven't seen since the 1980's (and are probably less equipped to deal with today).
So in the end, I'm going to have to say no. I think a cool-headed mobster like a Barney wouldn't even consider it. Sammy did the damage he was going to do and can't do any more. There is no advantage to whacking the guy now. If you do, you argue that you restore some of the Mafia's fear. But likewise you invite the scrutiny of the government to pin the murder on you. It's two sides of the same coin and it's a conversation devoted entirely to risking money and freedom than making money. With no upside.
In a word: no.
It's an interesting question though; even 20 years ago the answer may have been different.
The only caveat to my otherwise hard no is that I could see some lunatic who thinks they're in the mob or thinks they can impress the mob, or something like that, I could see some deranged person like that doing it. Otherwise, all these old rats are so irrelevant and are talking about stories from so long ago that while they are huge embarrassments they aren't worth deploying resources against today.
If Gotti never died from cancer do you think Gravano would have eventually been taken out? Interesting to think about as Gotti still would have been giving orders.
In my opinion no fucking way does Gotti go to his grave without having Gravano whacked. The only reason why Gravano is still alive is because Gotti passed away.
