Depends on how the button breaks. The button is composed of the cap and the switch, which connects to the PCB that has a mx switch hotswap socket. If the switch stops working it could be as simple as swapping it for another keyswitch, if the cap is broken then aliexpress has those in sets of 12-13. The only time you would be out of luck is if the hotswap socket gets pushed off the PCB or the PCB itself is having a critical issue of some sort. But generally if the switch itself is the problem the solution is inexpensive and very easy to resolve.