The lines of features, functionality, and price are blurring between cellphones and smartphones, but there are still many cellphones (check out my free phones and feature phones Holiday Guides) that are very good at serving as a phone that the majority of the people are looking for. Jeremy Toeman put together a good article that list how you can use even your current feature phone as a smartphone for many tasks that I think meet the mass market needs. I am reviewing the Motorola ZN5 and T-Mobile Behold and have to say there is some appeal to a standard cellphone.
However, I spend the majority of my phone time in the land of wireless data and I actually do need access to viewing Office and PDF attachments, communicating through my Exchange server, and many more functions currently available primarily through smartphones. The great thing about the mobile world is that there is a huge variety of choice so there is something that meets the needs of everyone and NOTHING is the "killer" device for everyone.