I agree, but my point -- to address the original question -- is that the incentive to make progress on the task list is reduced if it is not going to generate additional revenue, which it won't under the rental model.
I don't agree. Adobe's new incentive under the CC model is to keep users subscribed (as opposed to purchasing upgrades). These sound related but they're a bit different. Keeping users subscribed is best done by keeping users happy, which means listening to the users and working on the features that will really make a difference in their day-to-day use of the product (i.e., identifying and fixing common pain points, improving rendering performance, refining existing tools -- not just building brand new tools, polishing things, etc.). This is a rather different view of improving the product, compared to developing whizzy "headline" features that are intended to drive upgrades.
Btw, Thomas elaborates on this distinction in the video interview that Michael recently posted.
As an example, Camera Raw 8.2 (scheduled for release any day now) will have some minor refinements compared to Camera Raw 8.1, all of which originated as feature requests from users in this forum and elsewhere: a feather control to soften the blending for the spot tool, improved low-frequency noise reduction (color blobs), improved auto exposure, an improved white balance tool, the ability to create presets for batch-saving images, and a couple of other things. None of these items are great innovations, nor would they make a top-ten list of features for driving an upgrade. But they are (I contend) useful little features that do make a difference in the day-to-day use of ACR by photographers.
This is the sort of stuff that I feel we (engineers on the ACR team) have an incentive to deliver on an ongoing basis.