I anticipate that this scheduling conflict will be a dilemma for several teams, in addition to the FIRST and VEX organizations and volunteers.
* What guidance would drive the decisions your team's leadership would make in this scenario?
I don't think there's a sponsor in the world that wouldn't understand that participating in the World Championship for your competition (the one that they are sponsoring you for!) is a higher priority for your team.
* With respect to team sustainability, is a single sponsor equally important or more than a team's continued competition success within its local community?
This is a complicated question. It is unlikely that it is as cut and dried as "if we don't sacrifice Championships, we sacrifice a sponsor". I'm sure there will be other opportunities during the year to show your gracious appreciation and support for your sponsor. (If the sponsor you are alluding to is who I think it is, then I know that this is the case for a fact. Moreover, there are plenty of other sponsored teams that can't attend the festival for plenty of valid reasons.)
* What points would help us explain to our other FRC sponsors that we simply chose not to go to the Championships when one of our mantras for success has been going to the Championships every year via at least 1 of the FIRST programs?
Not sure I can help with this one. Other than to suggest that you avoid this outcome
