Well, better than a regular 321, such as what AY currently flies. Since they are specifically configured for premium routes for AA, they are quite low density. F is 1-1, J is 2-2, and they throw in some MCE (extra leg room) rest is Y.

I have made my comments on the possible configuration of the AA 321XLR in their forum. I think that to be competitive, they will offer 12-16 lie flat 1-1 F/J seats, 8 PE seats, 12-16 MCE and rest regular Y. Mind you these planes will be able to fly routes of 10+ hours. They are also considered a direct replacement of the old 757 single aisle, with further range and way lower fuel burn.

If AY were to go choose this plane for thin routes, I suspect they will offer a proper lie flat seat configuration for J, probably throw in some PE as they have announced it as a future option on other planes. Otherwise they will not be competitive for connecting business flyers using the benefits of HEL to Asia routes.