Ryan makes some good points, including the worry that many apps will be rejected based on what they do. He does start off with one very incorrect and misinformed point though.

Regarding Adobe's willingness to give up a huge chunk of change to sell high-priced apps in such a store. You better believe they would, because it's the same (or less) money they give up selling the same software in a retail box at a brick and mortar store.

Whether Adobe does or doesn't participate would hinge on many other factors outside the one Block first mentions. First off their apps would be rejected for using custom installers. Then for requiring serial numbers and activation, starting up background processes (this is easy to fix), no buggy performance (many of Apple's own apps would not pass here either), etc.