I question whether it will sell. You are giving up the slimer grip of the 220 for a wider grip but only gaining 2 rounds. Not claiming to be a marketing expert but I just don't see it being a good trade off.
The P227's grip will be slimmer than the P220's grip. It's based off of the P226 E2 grips. The standard magazine will hold 10 rounds, with an optional 14 round extended magazine.
Will it sell? I know I'll be purchasing one when it comes out. I love my P220 and I think the P227 will make a great addition.