In past few weeks we have learned that Stevie Crea went to a social club in the Bronx for a meeting with Bonannos. He wasn't tailed there. So it seems the bosses aren't too worried about surveillance. A proper Five Families Commission meeting in 2016/2017 would probably look like:

Genovese street boss Peter DiChiara (Doubt Liborio Bellomo is meeting with anybody outside his very immediate close circle).
Gambino underboss Frank Cali (or Dom Cefalu if he's still acting boss).
Lucchese acting boss Steven Crea or Matthew Madonna
Bonanno acting boss Joe Cammarano Jr.
Colombos...?