It would appear that those are all the Voice Actor Guests, as FunPub are now starting their Comic and artist guests.... which has been their way of padding out the guest roster in the last couple years.

First one is IDW writer James Roberts, and since we are back in California, expect most of IDW's writers, artists and editors to be at BotCon... but a fan convention is where you'd want to meet them, so it is a good idea to have as many as they can get.
The question will be if they have an IDW tour again this year, being three hours from Pasadena.