I have absolutely nothing solid to base this on but my hunch is that Tennant wins big. She's twice won over 60% with Obama at the top of the ticket plus there's probably a reason Capito turned down great opportunities. Has she ever even had a competitive election? Plus the vibe I've always gotten from her "star status" is paper tiger inside-the-beltway hype.
If Walsh gets in we will have a net loss of minimum 2 seats, SD and Ark.
Arkansas is not gone by any remote stretch of the imagination. Montana will be tougher, even with Walsh. Only South Dakota is really gone, right now.