I agree with putting Joshua Johnson on at 5P, they can do what ever they want with Chuck, I certainly wouldn't miss MTP Daily.
Personal I think they should re-do the schedule to what I have below:
Deadline WH viewers are familiar with John Heilemann so that would be a easy change at 4P, Joshua Johnson would be a refreshing change at 5P compared to MTP Daily, regular viewers know and love Steve Kornacki and he filled in for Hardball so it makes since to put him at 7P, moving Nicole Wallace to 8P would be great lead in to Rachel and she would bring in new viewers who don't normally watch MSNBC primetime, and lastly, since Lawrence O'Donnell has indicated he would like to retire in early 2021 (post inauguration) moving Chris Hayes to 10P would help his ratings with Rachel becoming his lead in and since All In is geared towards younger viewers he would be more poised to achieve that and receive a nice ratings bump from Rachel.
Leave Ari, Rachel and Brian where they are and the focus on stability and filling the open slots on the daytime schedule daily left open by Ali Velshi and prepare for Andrea Mitchell to retire. Give Chris Jansing an hour or 2, expand Stephanie Rhule's slot and figure out what you want to do with Katy Tur, Hallie Jackson and Craig Melvin going forward then fine tune the weekends so you can really compete.
The schedule would be:
4P-John Heilemann
5P-Joshua Johnson
6P- Ari Melber
7P-Steve Kornacki
8P-Nicole Wallace
9P-Rachel Maddow
10P-Chris Hayes
11P-Brian Williams