"Only" handwaves away a lot. It would put the characters into public domain and rob the authors of the ability to sustain themselves selling collections of early strips.
"No one will consider it authentic or canon." Citation very much needed. When there's demand for something, people will take what's offered. I would be fine with some sort of easy licensing scheme that would allow others to write stories, etc., in someone else's universe / with their characters... but they should see a taste. Especially when we're talking about mid-tier or lower-tier creators who are probably depending heavily on that large body of work to keep the lights on.
> It would put the characters into public domain and rob the authors of the ability to sustain themselves selling collections of early strips.
That's not true. It might make it harder to make as much money, but there's nothing that says the author can't still profit from selling something after it's in the public domain. I've paid for works in the public domain multiple times, sometimes directly to the author of the work.
Creators have a massive advantage when selling their own stuff. They can include things like signed copies and extras that no one else ever could. Fans want to support the creators of the things they love because they want more of it.
> "No one will consider it authentic or canon." Citation very much needed.
I'm not saying that you should be able to claim yourself to be walt disney, but you should be able to sell a hand made mickey mouse plushie, or a mickey mouse comic (under your name). That's different.
There's a lot of Girl Genius stuff on AO3. The Foglios (authors) seem okay with fanwork existing (there's even a fanfic-discussion channel on the semi-official Girl Genius Discord server). Of course, stuff on AO3 doesn't make money, which may be a sticking point.
"No one will consider it authentic or canon." Citation very much needed. When there's demand for something, people will take what's offered. I would be fine with some sort of easy licensing scheme that would allow others to write stories, etc., in someone else's universe / with their characters... but they should see a taste. Especially when we're talking about mid-tier or lower-tier creators who are probably depending heavily on that large body of work to keep the lights on.