Schoolhouse rumor is md88's start retiring after the summer, gone by year's end 2020. 90's start retiring 2021, and gone by year's end 2023. Rfp for replacement "upcoming" as they don't currently have a 150 - 160 seat aircraft on order to replace. Neo 320's or 737 max 8 were mentioned. Will probably come down which is cheaper.
Again, schoolhouse rumor, so g take it fwiw. 5 year plan changes weekly.