With the introduction of the overtake button in F1 2020, I think now it will be the perfect timing to make the LSB and RSB buttons enabled and available for the future games in Xbox One.
It was very complicate to attribute buttons without those two in the previous games and now with a new interaction it will be even more
[ For example:
A is looking backward
B is interaction with the HUD (engine, temperature, choice of tyre etc...)
X is change the camera
Y is the DRS button
D-Pad for changing the fuel, more FW, change break balance ...
Back is for the engineer or maybe for the flashbacks ]
We don't have any other button available for the overtake button except the RSB and LSB buttons (which can be used in Project Cars 2 for example).