@ TomSEA
Bing can gain market share by improving it's search results, which won't be a game changer since Google is improving it's search results at the same time.
Bing can try and attract advertisers with lucrative deals, but this again won't be sufficient alone, since Google has higher ROI and isn't sitting idle with it's advertising platform.
Bing can attempt to tie-in with it's PC, Phone, and Tablet offerings. Again, Google is right there with it's own tie-ins.
The only way Bing can win: stay relevant until one of it's sister properties gives it a competitive edge that Google's stronger market position and tie-ins can't out maneuver. Part of that involves R&D spending on things we haven't heard of yet, that might be tied to Bing's payroll but are being executed by another group within MS. And MS 'ate' the costs of launching the XBox platform before it started making money with XBox 360, so it very well might be that Bing is expected to be a cost-center that keeps MS relevant in Search while it develops the successor that will really take on Google (as a whole, not just search).