This is just a sort of notification.
MyBB 2.0 is being built from scratch, so your plugins + themes won't work on it. So don't spend your precious time making some big plugin for 1.8 series
The template engine used will be BLADE
The framework will be Laravel 5
That's all.
So please stop spending your energy on 1.8. It's of no use. It will be discarded sooner or later.
Regards.