You can still book awards using Alaska Mileage Plan miles for British Airways flights from the U.S. to Australia via London.  Yes, that’s the long way around!  At least twice as long from the West Coast of the US than going Qantas directly. 

But according to this Flyertalk thread (and confirmed on the Alaska Airlines website), the option will be going away August 31st. (You can redeem for travel past then, but August 31st will be the last day to book.)

Alaska’s partnership with British Airways continues, as far as I know, they just won’t allow you to book Australia awards. While it’s a lot of flying, it’s also quite a redemption value, spending 150,000 miles for all that first class flying. First class was just a 50% premium over coach (business class a mere 25% premium).

It’s never great to lose options, though I suspect this one won’t effect a ton of people. I lament its passing, though, because BA’s own members had to spend nearly 3 times as many miles in the Executive Club program if they wanted the same award….