Veteran color/rank/PiP should stay.
Just like you said this site would fail without script writers, wouldn't this site lose its taste without appreciating veterans who supported OSBot from the beginning?
I personally believe that all staff should have their own rank PiP and Color, as well as a symbol. It would definitely distinguish them from the other members of the community. The only problem is the huge amount of staff ranks there are: Trial Mod, Mod, Super Mod, Admin.
I also believe VIP and Sponsor should have their own rank PiP and Color too, basically agreeing with what you said.
What I urge the most is to have a developer PiP and explicit color. When a new member wants to join this forum, they mostly likely want to know who is in charge quickly or developed the program.
TL;DR
Too many staff positions, veteran stuff stays, developer PiP possibly