I just read his letter to his Greenlight Capital constituents, and it mentioned his "bearish" stance as well as his 12 year short position on MBI, which he finally exited. Einhorn doesn't cover until there is a large downturn in stock, so he won't be covering anytime soon here.
This could easily force him to cover without choice before the alleged drop. If he has a million shares short, he lost 20M in a few days. And if there is a stock split, you can bet losses will be quicker.
He could get buried here because this is potentially, a 200.00 stock (based on Starbucks price per share) and could even be higher. I'm sure he'll be buying a ton of call options to hedge his short position and wait this out until the major dip you mentioned.