If things are so haphazard for arm, then it's amazing anybody developed a product for it.
GCC is installed on my rpi in raspbian automatically, it works, and it's reputed to generate pretty good code, at least for bigger processors. I would be amazed if it didn't exist on EVERY other Linux-based arm OS.
Based on that, not knowing anything about sublime's code because I haven't seen it, I'm guessing that if sublime was written in C or in any of the languages typically supported by gcc, then the "wildly different architectures" argument holds little or no water. You (sublime) could just use the libraries which come along with Linux to support the Linux platform. If you don't use gcc or open source libraries in your code for other platforms, then you need some sort of middleware, a thin facade that converts the library your sublime app expects into what open source libraries provide. I know exactly what that involves because I do it. Also, that guarantees that your closed-source code is protected from any toxic open source license, because you already have a non-open source library you're using and you're linking dynamically.
So how's this for an idea?
- Build your closed-source product for a few specific arm processors, possibly using gcc if nothing else is available.
- Open-source the middleware library
- Let individual groups modify your middleware for specific platforms.
One thing that Open Source groups are really good at is porting something to a new platform. Sublime is about the best gui-based text editor out there, especially if you need a light one that's tuned to your specific needs. It's what arm-based nano-boxes need.