F1: if Red Bull and Pirelli leave F1, what do they do next?

Pirelli appear to have joined Red Bull and their stablemate, Toro Rosso in actively considering their future in Formula 1. MotorSportNotes examines an intriguing – if unlikely – scenario where all could come together with spectacular results. All out of options? When pretty much everyone significant at Red Bull starting sounding off about their future…