The one time fee makes me a little doubtful if this project will really continue. Especially because it seems to me you are selling less quickly than you hoped for (only 25% of the 'early bird' packages are sold after being 17 hours on an important channel for such product).

Maybe you should explicitly commit to X blocks and X templates within X time? X year(s) of support for Bootstrap 4.x?

I like the idea but am not sold yet for those reasons.

Another thing: there is nothing about custom theming. Do you use css vars, so I can customize a color in one place? Some source code example (downloadable?) would be helpful. Maybe one template with its different blocks to give out for free as an example for the rest.