I may be totally off base here but here is my speculation regarding the Rouge expansion--of course I am always ready to be corrected:
1. AC and the Unions have had issues with benefits and pension plans
2. Rouge was started with staff taking less pay and presumably less benefits to make the leisure market viable. The mainline union rules do not apply here
3. AC cannot fire mainline staff but they can be laid off if there is not enough work
4. If Rouge can provide Canada/US wide services AC's costs will be significantly reduced--ergo more profit
It, therefore makes sense to replace NA flights with Rouge and reconfigure cabins--even temporarily--to justify eliminating J class and then rise again like the phoenix and be a new, profitable AC
I have NO sources on which to rely on and is just basic speculation. I am quite ready to be proved wrong.