All the conversions are expected to be finished by May 25th.

They are converting one aircraft type at a time, starting with the 900's.

Please keep an eye on your reservations as the conversions happen, as there may be some seat disruption if you are currently seated in a row that will no longer exist

(it sounds to me like those assigned the current non-exit rows 16 and 17 may be relocated to the brand new row numbers that will be created in the back of the aircraft)