The Barese crew was said to be the biggest in the family and we only saw two other guys besides Larry. Albert and Rusty Irish. Junior had a pretty large crew himself in season 1:

Mikey
Chucky
Patsy
Philly
Bobby
Gigi
Beppy (not Sasso)
Tommy
Murf
Bobby Sr (semi retired)

Plus a few other unnamed guys hanging around him in those early episodes. Presumably they were either whacked or they were among the "13 others" arrested in the scam with Junior, Larry, and Beppy Sasso.

So his crew was huge and Larry's was even bigger. What would Larry have had, fifteen or twenty guys?

Also we never saw any of Ray Curto's crew besides the Capo himself. He wasn't Capo over nothing so there had to be plenty of soldiers and associates there.

We skimmed the surface with the Altieri crew as well, just Jimmy, Carlo, and Walden. And Tony B was apparently working with them as well. After Vito is outed, Carlo says the guys in Vito's crew weren't going to respect Vito anymore or something like that. By that point, the only other known member in Vito's crew, Eugene, was dead. So there were others we never saw.

My point is there's much more to the family than what we saw. We mainly know of the men in the two Soprano crews, and Aprile crew. There are probably plenty of other guys to take on leadership positions. The family is ok. Smaller than they were in 1999, but no worse off than other small families like the Patriarcas, Philadelphia, or Detroit. Or the real life Jersey family. They won't be disappearing any time soon, nor will they get taken over by the Lupertazzis upon Tony's death. I don't think the other New York families, or said smaller families would stand for that.

As for Carlo flipping, who knows, with the luck that family had with rats being put out of commission, maybe A.J. accidentally ran him over with his huge yellow SUV while Carlo was crossing the street with his handlers. Problem solved.