Way back when Akamai was starting up, I figured it wouldn't have much of a shelf life, because people would soon start writing cache-friendly pages, and cache servers would make Akamai's core service obsolete.

I still think a cache network would be superior, but Akamai isn't going away any time soon.

Similarly, I think you're in for a surprise as to how slowly change spreads. Corporate environments will likely use Outlook way past its shelf life.