There are six more days of nail-biting ahead for Apple (AAPL) and HTC.

A final decision on a closely watched case before the International Trade Commission that was due on Dec. 6 and then postponed to Dec. 14 has been postponed once again to Monday, Dec. 19.

This is a big one.

In the worst case scenario for HTC — the Taiwanese manufacturer that sold 5.7 million smartphones in the U.S. last quarter — the trade commission could ban the import of HTC’s Android phones at the height of the holiday selling season.

It could also force Google (GOOG) to design workarounds that would, in chairman Eric Schmidt’s words, “limit your choice.”

An HTC win, on the other hand, would be a setback for Apple — and for Steve Jobs’ vow to destroy Android to his “last dying breath.”

As FOSS Patents‘ Florian Mueller writes, somewhat hyperbolically: “Apple will either have to fend off the fundamental threat that Android represents and ensure product differentiation or its own stock price will go down the tubes.”

For background on the case and the language of the two patents at issue, see here.