Thanks for all the comments, it’s encouraging to see.
re: working with the current GUI, rather than replacing it. These are all very good points, I’ll put some more thinking into it.
re: open source. I’d rather see Sublime open sourced rather than abandoned, but it is a commercial venture, and it just doesn’t make any sense to both release it as open source and continue working on it.
For interests sake, last time I counted, Sublime was around 70k lines of C++, including blank lines, comments and unit tests. Python is used as an extension language only, and it’s use is pretty much what you see is what you get: all the Python source is included in the distribution.