I dont think that is possible with today's technology vs. the limitations posed by the MacBook's physical size (see the video of the teardown of the iPhone X - the components needed for FaceID are not small by any means!!!)
Additionally, I'm not sure if Apple would offer a quad core rMB before offering a quad core MBP13TB/13nTB, and further, with no perfectly suitable quad core for the TB version yet released, I'm not sure if Apple will offer a quad core nTB before they offer a quad core TB.
Even if the above is all doable, there is still the issue of cooling; with the passive cooling of the rMB, even if Apple could get a quad core CPU inside, it may not have significantly improved performance over the current m3/i5/i7 chip (these are all the same chip-just different binned specimens) for anything other than extremely short periods of burst performance. The gains for what could be a high pricing premium for the higher tier CPU might be very limited!
Even if that is possible, then there is also the issue of battery life, and how something like the i5-8250U could consume more than twice as much energy as the current CPU. For a design that prioritizes portability over power, a massive hit on battery life might not be an acceptable tradeoff to many owners.
Ultimately, I really don't see this happening within the next 15 months.