It's strange that literally no one has mentioned the fragmentation that would occur if they updated the rMBo with OLED Touch Panel and kept the rMB and MBA as is.
Unthinkable. It would be a bit like having "force touch" on the iPhone, MacBook and MacBook Pro but not on the iPad, and a Pencil for the iPad Pro but not the iPad Air so that you couldn't have common UI standards across devices...