Shared hosting companies are doing quite fine. I think you'll find the users on shared hosting are wildly different from those on EC2/Heroku. Maybe someday when they are equally easy to use, but right now, as a small business owner or kid making a website, I don't want to think about hourly billing for my website.
I believe that simple economics will kill the shared hosting company, given enough time:<p><a href="http://clubtroppo.com.au/2008/07/10/shared-hosting-is-doomed-and-i-have-the-graphs-to-prove-it/" rel="nofollow">http://clubtroppo.com.au/2008/07/10/shared-hosting-is-doomed...</a>