[1]: https://www.adobe.com/devnet/articles/crossdomain_policy_fil...
Sure, someone has to run that proxy, but I'm sure flash games sites wouldn't have trouble doing so.
It's kind of a moot point, though; I doubt that the networking servers that these games depended on are still online. That's a whole separate preservation problem.
Alternatively, figure out a way to ship remote dependencies alongside the swf file, and define a patch format that allows replacing network requests.
All of this is more work to do, but all of it is also workable solutions.
There is a parallel universe somewhere where Javascript was designed as a Turing incomplete basic interactivity template and now node runs ECMAFlash2019
At the same time, I don't want to be dogmatic about anything, those are just general tendencies. Emacs for example is a beautiful example of an almost opposite design. The software is like a computing instrument that the user has to first learn how to play, but the more effort they put in to it, (up to a point at least, and depending on what they want to do) the more they get out of it. Ultimately it depends on what you're trying to accomplish and who your users are.
I've watched a few products "grow" using this method then project managers be surprised when down the line it's all held together with duct tape and chewing gum and a "simple" change is a week of work. There have been a number of times in my past where I have purposefully not suggested or the team decided not to bring up an "option" because we knew it would be abused.
He goes into some of the reasons it's a bad phrase and some of the problems behind it. I'd recommend the talk.
These are insanely hard problems yet they are solved because someone asked and someone tried.
For that you need server snapshot, that should be easy - just require it (maybe with source) to be provided with each application that use network. But some servers aggregate data from several users.
That's easy too - require it to be possible to deploy by user on some generalized network architecture.
We have same conversation again and again - The Right to Repair, Internet Archive, Open Source. Flash was part of that rhetoric too - that's why it is so polarized. Brilliant tool, so much creativity and yet closed source, poorly supported, bug ridden. It was a public stance - if Flash become standard it would be new IE once again.