I think this notion of a CDS will change. Not tomorrow but in the long run. Sites need to become more and more dynamic to provide new types of marketing. I blogged about this here:

http://mrtopf.de/blog/web20/what-is-the-future-of-content-management-systems-related-to-social-networks/

And Plone is actually in good position for that except for it's speed ;-)

Yes I know, you can enhance your CDS to be not static pages but a PHP app etc. but IMHO this makes the setup very complicated and probably never can be done completely out of the box. It also means that you might have different backends, different workflows etc. Usability will probably go down the hill. I definitely want a more integrated system. Maybe one solution would be to have a Plone light which is fast as hell but still can interoperate with it's big backend brother. (of course it's easier to get hosting for PHP than for Python but then again I think in this market it's not that important to have the cheapest hosting provider on earth but you will have your own specialized setup).

But of course if the general perception for some audience is that Plone is no CMS then maybe we shouldn't market it as such.