it's easy when you collect Schwinns, everything is available.
here's my stance on putting some sort of mark on reproductions.
1. if they're crap, they need no mark, they'll show their quality, or lack thereof.
2. if they're exact reproductions, I'm all for letting them patina in and blend in as real. in 50 years, John's parts will be indistinguishable from real, and will deserve to pass as real if they can. 50 years from now, if I'm still around, the two Super Streamlines I've made will most likely be sold and probably as real, or at least after an owner or two they will. at that point, I think they'll have earned their status as a real and worthy bike.
on the good reproduction parts, it's not like they're being made en-mass in China, they're being made one off, in extremely high quality. I don't think they'll hurt the value, not for us non-Schwinn guys who just want a chance at owning something really rare and hard to get.
you also have nothing to worry about, John doesn't like Schwinns, so no worry about him making brand new Aerocycle tanks (though I've wanted him to just to piss everyone off).