The new improvements in Mountain Lion for Dashboard seem to lend hope to it. I'd still have liked to see it default to being an overlay again, rather than a Space, as part of the usefulness of Dashboard is being able to arrange widgets around the edges, hit a key and have them overlaid upon what you're doing so you can quickly enter figures or text into the appropriate widget.
Casual users that aren't aware that Dashboard ever functioned differently are going to have trouble finding it as useful since they won't know to look for the option to change its behaviour.
Some exposure through the Mac App Store, and some extra javascript frameworks to make them more app-like would be great, as would some features to help people design better UI's for their widgets.