Does it?  I figured 12 or 16 came after 8 if it was deemed necessary (but obviously not anytime soon).  Going through all this hard fork rigmarole again later if the LN or subchains plans don't materialise just doesn't strike me as sensible.  Surely the more pragmatic approach would be to see what the average connection and bandwidth availability is later when we're approaching 8MB and have the option to keep going if it's safe to do so?  If we don't hit 8MB for another 5-10 years (or possibly longer), home internet packages might be vastly different to now and full nodes might be able to handle much more activity.  We might even have an "internet of things" where the toaster and the kettle have a full copy of the blockchain, heh.  If raising the cap too quickly is irresponsible because no one knows what the future holds, then a permanent fixed cap, by the same logic, is equally irresponsible.  Nothing should be set in stone.  It'll only cause potential headaches later.