Is it possible to to replace MacBook Pro Touch Bar keyboard with a regular keyboard?
The cost in parts and labor makes this cost prohibitive. Better to sell yours and buy the one you want. Specifically, the top case holds the keyboard and the logic board is different as are other internals. 

Anything is possible with several thousands of dollars (or more) of course but using an external keyboard might be the practical fix until you can get a swap for another Mac arranged.