To be up and running in 2016 means they need to buy a competitive team, Red Bull and to a lesser extent do Torro Rosso look the most likely, or an outside bet Sauber.
So Audi have one last swing at Le Mans, with Alonso as driver in one of the cars before rebadging an existing F1 team, kick out one the drivers and some of the management and drop in Alonso and Domenicali, then spend 5 years chasing drivers glory and umpteen millions of Euros before limping away at the behest of the owners of VAG, (who seem to be a bank and the people of saxony)
Oh and drop your DTM teams as well, sounds like a winning plan.
F1 if for drivers glory, Le Mans is for team glory.
However Audi did walk away from the WRC without a backward glance...