The Titan should be the most powerful GPU available until Maxwell / 9-series cards based on 20nm. These should start to appear in mid-2014, though that is all dependent on TSMC keeping to their current schedule for high-volume 20nm products. The "high-end" ~300mm^2 20nm chips from Nvidia and AMD ("GTX880 or HD9900) are likely to be around 8Bn transistors, and I would wager that they will outperform a Titan by around 10-25%. But that's 15-18 months away.
As for buying a Titan for 1080p gaming - I wouldn't, if value for money is a concern. If you have unlimited disposable income then sure, why not - it's a very fast card. But if you're looking for a 'bang for buck' solution then it's hard to see the value in shelling out over £500 (after the sale of your GTX680) for a 30% performance bump in the odd one or two games that a single GTX680 can't handle perfectly.
Thanks for taking the time to post these benchmarks btw gregster