That was the original plan, but I veered off to focus on doing one system really well. I figured if some company wanted to sponsor a port, I could do it, but otherwise I'd direct people to other compilers like LLVM-MOS. I do think it's possible to port, but it's not trivial. Some areas - like the linker - are very specifically designed for the NES.
You may be mistaken. Retro hw/sw and gaming is a booming business at the moment. Plenty of crowdfunded projects that have been overfunded and then delivered, and even consumer goods being shipped worldwide in major department stores.
This is a really neat project. It reminds me a lot of Inform, in the sense that a full “modern” language was designed around creating an older-style of game.