Volley, I'm going to "devil's advocate" you here for a minute:
Idaho jumped out of the WAC because they saw what the WAC was becoming: Chicago State, Grand Canyon, Bakersfield. That's not who they are. They put athletics with similar schools (Montana, Montana State, North Dakota) with the exception of affiliate FBS football in the Sun Belt Conference (SBC). They'll be content with that until the SBC gives them the boot (ala what the SBC did to Denver a while back).
However, with SBC football at 11 today, the SBC pulling in NDSU would give the SBC the magic number for a conference championship game. And it would implode your notion of Idaho football returning to the Big Sky (and serving as the catalyst to an FBS Big Sky).
Thoughts.