Stone cited potential uses for the planned paid services, such as airlines being able to analyze data from customers who subscribe to their Twitter feeds. In addition to those paid services, Twitter also has plans to begin licensing their content and streams to other websites, opening doors to work with news or media agencies down the road. Stone envisions news agencies using live Twitter feeds as part of their newsgathering, something that may be of use to a world where real-time news has substantial value.
Generating money isn't the only problem Twitter faces. While the service has a substantial user base, it has dealt with customer bleed from the beginning. The user retention issues do not help the claim by some, such as Nielsen, that the service is just a passing fad. Twitter also deals with a negative reputation in the workplace, where many businesses see it as a waste of time. It may be difficult to convince a company that it is a service worth paying for if it's something commonly banned in the workplace to begin with.
If Twitter can solve those concerns and manage to begin selling paid accounts, they might be able to convince the world, as well as their investors, that they can overcome their financial difficulties and questions over value. From an outside perspective, it seems to me that Twitter is still a dangerous prospect. People may lose interest, and without an audience, Twitter will not survive.