The company did say they were finalizing the 2019 fleet plan with delta in a recent vacancy notice memo. Would not be surprise to see something announced in the next few weeks.
My thoughts... Delta winds down the 700/900 flying by GoJet in DTW, shifts Skywest 900s from LAX and/or SEA out east to replace that flying (remember, they want the CRJ in the less premium markets). Gives us 175SCs to replace that scope and the vacated western flying, setting us up to take the rest of the trans states flying towards the end of 2019.
I think Delta and Endeavor are now hesitant about taking any used AC from GoJet. Too expensive to get up to our mx standards.