At this point, I'm not sure. Let's get 7.5 finished and out then we can really dig into 8.0. It's not going to take as long as the 7.0 rewrite took, I can say that. It is going to be a big upgrade though. Not only with the UI, but with the foundation as well. We'll probably end up trimming down or getting rid of smarty, put in support to use memcache, and alter a few database tables for better performance.

Once we really start in on it, I can answer that question a bit better.