As has been explained to me, the leases on the 200s were signed when fuel prices were high, thus the lessor had to set the rates pretty low. First lease expires in 2018, and there are more and more 200s in fresh paint out there.

That said, apparently it's pretty expensive to make them ADS-B compliant which is required by 2020.

When it's all said and done, we really won't know how those 200s will effect seniority until we know more about the upcoming "flow" negoiations and get a better idea what attrition is like going forward.