You overrate Raila and ODM. You're lumping NASA and CORD coalition as NASA - ignoring the role of Kalonzo and MaDVD in Raila's 45% - Raila has scored around 45% the last few elections in coalition with Luos, luhya, Kamba
and or Kalenjin.
Right now ODM have 62mps out of 290mps - so if parliamentary strength is an indicator of real ODM strength outside NASA - then Raila has 21% support base.
Jubilee won 140 out 290msp - and if we assume Ruto and Uhuru had equal share - then we are talking them controlling 25% each directly - obviously Uhuru is the past and Ruto is the future.
For Raila to win kenya election - he need 50% - from 20% - not from 45% (unless he was to retain NASA coalition
).
Ruto without Uhuru can easily start at 30% - and just need 20% to win it.
Which is why for Raila it's important to expand the Pie - and have PM, Deputy Pms and all sort of positions to be able to gobble coalition.
While for Ruto retaining Jubilee winning coalition is all he needs.
Unlike Ruto, Raila does not need to even run for that election. He can mess up for Ruto completely by tosharing someone else. Even if he runs he does not need to have a Mt Kenya DP. Ruto has no other choice. If he fails to name a Kikuyu, a big chunk will run away from him. Their support for him is not because they hate Uhuru or love Ruto so much, but believe after Ruto it is another 10-20 years for them. Also we will see how the Merus and Embus will react to Ruto's DP coming from Kikuyuland.