Left-Right combination is important so i think Kohli & co would prefer Shikhar over Gill and KL Rahul, at least for the 1st match. If Shikhar fails there then KL Rahul would get 2nd chance over Gill.
Shikhar Dhawan is in really bad shape and even his domestic team has decided to drop him. KL Rahul also seems to be going through a rough patch. If they want left-right combination, then rather than taking it as an excuse to include out of form players such as Dhawan/Rahul, they should go for Ishan Kishan or Devdutt Padikkal. Or Rohit can be dropped to the no.3 position to include Shubman Gill or Prithvi Shaw.