^ having the 404 run up to the 12/169 split is all that is really necessary, as well as returning 169 back to Provincial ownership. (along with a bunch of other highways such as 48 between 12 and 35) There isn't really a viable way through Orillia that would allow for a 404/412 connection to 11, so it would have to take the 169 route which is way too low traffic. Cottage traffic could be fairly easily fixed with an 8+2 HOV lane 400 to the 11 split, a 6 lane highway 11 to Orillia, and a rebuilt to 400 series standards 4 lane highway 11 to Gravenhurst. Maybe rename it the 411 at that point as well. (though there are still some at grade intersections further along 11, it is still good enough to have a 400 designation IMO) A lot of the bridges along 11 are seriously falling apart so I wouldn't be surprised if we see the 11 upgrading start in the next couple of years anyways.
also, the reason the 400 currently runs directly into 11 instead of through to the 400 is that back in the 1970's when 11 was RIROed the traffic was much higher going up 11 rather than 69, especially to Orillia. The traffic on 69 was very light back then, so it just didn't make sense to have the end of the 400 end by pointing up 69 instead of pointing up 11.