Speaking with SBS' Cycling Central program, the three-time green jersey winner said: "I realised in the lead up to the Tour and with the other riders in the team and what have historically been the goals of Johan Bruyneel's teams in the Tour de France that I probably wasn't going to get selected this year.
"Apart from their own tactic of more riding for GC and fully supporting the rider or riders who have a good chance to ride for the General Classification and reach the podium in Paris, the team has also heavily concentrated on winning the teams classification again as they did last year," McEwen continued, explaining that with a multi-pronged attack in Levi Leipheimer, Andreas Kloden, Chris Horner and Janez Brajkovic that all four riders were capable of standing on the podium in Paris.
The 39-year-old will instead focus on the Vuelta a Espana and then hopefully gain a position on the Australian team for the world championships.
McEwen faced the prospect of an early retirement earlier this year when he was left stranded without a team following the collapse of Pegasus Racing. A phone call to Lance Armstrong resulted in the veteran inking a one-year deal with RadioShack in January.
The 12 stage winner at the Tour explained "nothing's impossible" when it comes to his participation in next year's Grand Boucle but admitted he hadn't made any decisions regarding his future.
"I think I'm going to at least start the season, that's what I'd like to do, rider another Tour Down Under certainly," he said. "Beyond that, I haven't made any decisions – I'm not locked into a team next year, I'm not in any concrete discussions with a team for next year yet. So it's all a bit up in the air and too hard to say this early in the piece."