go G5. I first titled my OP as "potential game changer" for BYU. And it might be although I think the same analysis that keeps BYU Indy despite having to get an at-large bid for a NY6 probably keeps BYU Indy for an expanded playoff--even if G5 gets an auto bid. But it certainly raises the question.
But I'm also a big Indy Homer. Obvious disadvantages but I think BYU is particularly well-suited to be a FB Independent (since I see no prospect of BYU ever being invited to a P5).