Well a major optamist could conclude that it is possible for Sony to win but let me lay down the conditions Sony would have to meet within the next year.
A massive massive price drop, no not just a price drop to match the 360's pricepoint but to match the Nintendo Wii's price point. I'm talking a price cut to around 279CDN/USD to give it an edge against the vastly superior 360 software line-up and the Nintendo Wii's innovative hardware.
A couple major hits, no not just MetalGearSolid and KillZone2. I'm talking major hits like FinalFantasy13 a new KingdomHearts another GTA , GTA5 , ResidentEvil5. But half of those are multiplatform Sony needs them to be exclusives. A strong third party and first party exclusive line-up is needed pretty quickly to give the PS3 a much needed boost in the face of Master Chief and Mario.
A massive ad campaign and possibly the release of a new hardware model. This hype is needed to bring the PS3's deadly image out of the quagmire.
So after a massive price cut , drive for exclusive titles and an expensive ad campaign were talking a possible slim victory for PS3. Because even if Sony met all of those requirments they would still be up against the established user bases of 360 and Wii which would continue to be successful regardless of Sony's success. Lastly the costs Sony would have to pay to acheive a comeback would make a victory more of a loss for Sony.
In the end its in Sony's best intrest to cut their losses and accept defeate. Just keep supporting their platform and hopefully they will be able to match GameCubes success last generation!