Just recently Individual Computer released a C64 motherboard replacement that is cycle compatible with the original, with the original IO ports etc.
On top of that there are about a dozen FPGA boards with a wide variety of C64 cores that will also give you more or less (depending on version) cycle compatibility with the C64 and varous degrees of availability of ports.
I think you underestimate how long hardware compatible with these systems will be available vs. the effort that would be involved in keeping an emulated setup working across migrating hardware and OS models and ensure the hardware interface they need keeps working for each new generation.