If the SID can be emulated in software then so can a VIC-I or Ted chip.
I am looking at used Commodore systems in eBay, it seems the chips and keyboards are worth more than an As-Is used Commodore system. Getting a C64 Reloaded Motherboard and adding in the chips from an Old 64 seems to cost more than a Mega65 system.
So the used chips are expensive, someone could make a VIC65 system using older chips and a GO20 mode to go into the VIC-20 mode, but you would have to do a feasibility study to see if it is worth it. The VIC-20 had a different cart slot than C64 as well, etc.
My advice is to support the Mega65 project and see how well it does before making the C16 or VIC-20 versions. The majority of people want a C64/C65/Mega65 system because it has a large collection of software behind it. C16 and VIC-20 never had GEOS either that I know of.