It is an interesting concept. If I understand FAQ point 1 it correctly, you want to avoid using current web technologies and create some kind of browser on your own?
I think (at least for the beginning) it would be better to use current web technologies (and maybe in not so distant future some technologies like webassembly/asm.js). The reason is quite simple - current web platform has very good support among many different systems and devices. You will be able to target desktop and mobile clients with very little effort.
Writing your own browser is very difficult task and you would have to write it for many platforms. (Of course, the main core could be created in multiplatform way and only some platform specific things would have to be developed for each platform). And in some way it would be reinventing the wheel anyway.