Number of coins here is enough I believe, it is already stretched thin accross the board and if you add something new, yolodice has to put up all the bankroll until people start bankrolling it themselves, which means a ton of money from yolodice going out for a while, they are known to allow us to be the house and that is why it would be a very painful period for them to be the bank and the casino all the same time, not that it is rare because there are tons of places that bankroll themselves but yolodice allows much much higher max bet which is why a HUGE bankroll is required.

Adding a new coin would make it a bit more difficult and that is why I believe the current system is working so perfectly anyway and that means there shouldn't be a reason to keep it going for more.