I doubt anyone will be using this technology to manufacture firearms for mass retail sale. PIM is definitely a better process for that and I don't see this catching up in that regard even as this technology improves, but...
I think the injection mold press used for the AR lowers probably runs about $250,000, based on my limited knowledge of injection molding and guesses as to pressure and mold size. The mold then costs $35,000 for a "cheap" aluminum mold. Then look at EPA requirements for the operation, infrastructure requirements, etc. Especially power.
If you want to build one yourself, and many do, this option is a whole lot more attractive.
Making a model and then a casting is an interesting option. I wonder how a glass lower would handle 22lr..