I came across this piece from Harvard Business Review (HBR) about the future of solution selling. http://hbr.org/2012/07/the-end-of-solution-sales/ar/1

They suggest that buyers are becoming better educated and able to find the solutions to challenges themselves and therefore do not need a solution sales person to help them. However, they also set out how sales people are adapting to this with more sophisticated targeting of clients. Definitely worth a read.