If they do refresh the 13", it will probably just be the processor in the same chassis. If they made a 13" MacBook Pro with the new design, keyboard, chassis, and display, it would probably eat into the 14" MacBook Pro sales. And not sure if they'd use the keyboard that was once used in the non-touch bar model, or keep the touch bar alive (also doesn't make sense).
With the new Air coming out - I think this will fill the 13" category for Apple and the 13" MacBook Pro will eventually be killed off. I personally would like the 13" MacBook Pro turn into a 'MacBook' for those who do not need a Pro, and doesn't want an Air based on the current design rumors. Kind of like a middle-ground Mac.
I would love a new thin and light MacBook, but I've become so spoiled by the MicroLED displays in the new Pros. If the new Air or any new MacBooks do not have a MicroLED display, not sure if I would be interested (as much as I would love and super thin, light and cool running MacBook). Going from my new Pro's to my M1 Air is night and day (in terms of the display).