Barnes had initially suggested he would wait until after the 2013 domestic season before announcing any future move but it now looks as though he will be playing his trade in Asia from September.
That would mean he would be unavailable for the Rugby Championship, leaving the three Tests with the Lions on June 22, 29 and July 6 as his last chance to shine for his country before his move overseas.
If confirmed as expected, the news will be a big blow to Waratahs coach Michael Cheika on the eve of the new season.
It will also be particularly disappointing for Wallaby boss Robbie Deans, who has been a long-time admirer of the experienced utility back.
Barnes hit a half century of caps on the recent end-of-year tour of Europe and is now one of the most experienced players in the current Wallaby squad despite being just 26 years of age.
And while his age means a return to Wallaby colours at a later date is still a real possibility, it will be interesting to see if the announcement affects his chances of a starting spot this summer.
The versatile star already faces a tough task to see off the challenge of Kurtley Beale and Quade Cooper for the No10 spot, or the likes of Pat McCabe and Mike Harris for the inside centre berth or even Adam Ashley-Cooper and Beale for the No15 shirt when the Lions head to Brisbane in five months' time.