Any reason some kind of Kickstarter-like service couldn't help with this? There are a couple interesting economic tricks going on in various Kickstarter projects that could be applied to this.
Developers publish feature lists for an upgrade cycle, users vote with their dollars, different features can be funded, etc etc? There are a couple of open source projects (like PostGIS) that have similar programs...
The quality of Sparrow is it's simplicity. Adding features to it would make it evolve in bloatware. See MS Word. They now reshuffle menues to justify upgrades. I guess in some next version, menues will be at the bottom of the window.
This is not a long term solution. The only viable solution was to reduce burn rate as close to zero as possible. This means producing a new software.
Developers publish feature lists for an upgrade cycle, users vote with their dollars, different features can be funded, etc etc? There are a couple of open source projects (like PostGIS) that have similar programs...