And with 70.3 moving to Austria, since worlds was practically a free ride this year (depending on AG) next year you probably get in just for showing up! :)
The 2015 allocation (for Austria) of slots for North American races is pretty low. Most races get 30. I suspect they will not be that easy to get.
As for being a free ride this year I am not sure this is everywhere. As a matter of fact races like Syracuse that normally don't sell out have this year because they have Tremblant slots.
The roll down process is weird. You get one AG with more slots, a few top performers don't show up for awards and there is a deep roll down. But it's more the exception than the rule. There are many people that finish 10th, 11th...whatever, hoping they will get a spot and don't. For example I don't think St-Georges rolled down very much.