That's only partially correct.
On the regional side, the plan is to retire 112 aircraft in 2015 and add 49 EMB175s. That's a net loss of 63 aircraft; ~11% of the regional fleet.

Mainline is adding a net of 21 aircraft in 2015.

Spin it however you guys like, but it appears that some regional flying is moving to mainline. This is backed up by the Feb operational performance report (the most recent) showing a YOY decrease in regional RPMs but a YOY increase in mainline RPMs.

Looks like some regional to mainline upguaging with frequency reduction to me.