For those who are interested, though I don't have a link, Krin was talking a bit over at Krinlabs about ideas he had for the Sonny series
One thing he mentioned was keeping all the classes now and adding a 4th in Sonny 3.
Of course, as of right now, development isn't even being planned, just ideas. Don't expect it anytime soon, in other words.
Other ideas included stuff such as summonings, which took the role as other team members.