Nice they kept Ursula as a separate character at the very end, they fooled us with the "Regina is Ursula" thing.
I knew going in that Ursula was going to be a separate character. They announced a couple months back that Charisma Carpenter, Cordelia from Buffy & Angel, is playing Ursula.
As for the speculation, I'm not sure that any of the main characters would be left behind as it leads to some problems if they ever want to bring the actors back.
What happens to Pan if his shadow is captured?
And we still need to see Greg's shadow again.