That's a great question. As of now we have almost 2800 pilots. To upgrade we'd have to have over 5000. I don't think we are going to have that many with the current orders. We are a young pilot group, so not too many retirements in the next 10 years. If I were to guess.... About 5-6 year upgrade if you're lucky.

There are guys much smarter than me on here that may have a better answer, hopefully they'll chime in.