Regarding open-sourcing TextMate: I disagree with Charles - open-sourcing TextMate would not necessarily "make it go down the slippery slope". Open-sourcing your app does not mean giving everyone commit rights. Most successful open-source projects are led by a "benevolent dictator", who keeps close tabs on what goes into *their* project.

While I do not have an answer to Allan question regarding the business model, I'd love to see TextMate open up. Maybe Allan could go the Safari/WebKit route - open-source the text editor component (the NSTextView replacement), but keep the application itself commercial. This would allow other projects to use the excellent editor component, including other competing text editor apps, but I assume most power users would still want to use the original TextMate.

If the editor component was licensed under GPL, Allan could prevent commercial competitors from using it. Of course he could still license it to commercial competitors for a fee if he wanted to do so. And once it dominates the market (GPL or not), Allan would of course be the leading expert and would surely not starve..

There's lots of options to be considered!