I was really surprised that Bovaird was the 4th Zum line.....no particular reason but I always thought that a balance between north south and east west routes would be more effective in driving ridership.....so when I heard/read that it had a north south component to it I assumed it would be airport road....so this change makes some sense. Sure there are not a lot of people living on Airport road but there sure are a lot of employment lands there.
ksun is right, I think taking the route back west on Steeles to the Bramalea station makes little sense to me....if someone on the 505 wants to get to Bramlea they can easily transfer when it crosses steeles onto either the 511 or the 11. What makes sense to me is taking that 505 beyond Steeles to the Malton GO station and, if possible/feesible, to the airport itself.
If you could get it to the airport it would, either, augment or replace the 115. If the 505 went to the airport, BT would now have an airport service that serves far more people and intersects with both of the other East/west Zum routes.....I wouldn't take it into the terminal...just to the end of the airport people mover by the discount parking lot.