The second season of Mixed Match Challenge ended this week on Facebook Watch. That show is the reason why 205 Live was moved to Wednesday since WWE needs to provide live programming for Facebook Watch and it wouldn't make sense to do 205 Live after fans have already sat through two hours of SmackDown Live and half an hour of MMC.
As reported in the Wrestling Observer Newsletter, the decision was made to keep 205 Live on Wednesday's for the rest of this year. Rather than doing the show live, the plan is to keep taping the show before SmackDown.
A decision has not been made on the timeslot for 2019 but it is worth noting that the viewership first increased when it first moved to Wednesday but it has dropped to a very low point.
At this point, it seems like keeping the show on Wednesday at 7 pm eastern is not the best idea.