Maybe it'll work, maybe not. I'm just discovering this (and Flarum), and whatever the road maybe we'll start to see at least one maintained light and fast forum software with clean elegant code and good flexible solutions. We've just been waiting for it since 2008 (and PunBB 1.3 alpha).
One such project will live or die with its main extension. As much as possible outside the core and everything in plugin is far from a new idea, and usually project die because a key feature is missing, or because the core team believe that critical extension will just happen. They won't. They need to be designed, re-designed with the community, written, tested and maintained as fast and as good as the core.
Even with a system as simple and user friendly as extension handling Wordpress for example (and that's still a lot of work to make it happen), no one wants a headache because the core is at 1.51 but the avatar extension isn't tested after 1.4 and the XML sitemap extension updated to core 1.51 is not compatible with the subforum extension which is the only one but has ads in it and doesn't play well with the split&merge extension which by the way has a core 0.9 backend style that clashes with 1.51. And so on.
Everything outside the core is quite fine from a pure coding point of view. The average administrator should not have to worry about it, at all.
However, I'm a bit skeptical about the amount the amount of javascript in these current Flarum forums. If the project entice me to keep updated, or even get involved, I think I'll test Flarum with my old eeePc. That very low and weird screen resolution, coupled with a old browser and an extremely lazy cpu is usually a good test of web design.
