Now that Adobe is killing all things Flash, what will happen to the (must be about 200million) .SWF files out there that need to be edited and updated if any UI elements are going to work in almost every video game available, plus too many other existing applications to imagine?
How can SWF filesbe created and edited now?
SWF is actually an open format. There are both existing commercial tools (Adobe Animate, Flash Builder, Flash Professional) that edit SWFs, and some open-source tools. That said, your post highlights the forward risk that staying on deprecated technology will become increasingly painful, if not impossible. There are things you can do to buy yourself time (make a VM with all the stuff you need to edit SWFs, etc.), but ultimately, you're going to be better served in the long-term by moving to modern formats and workflows.
Just to clarify, Adobe isn't killing all things Flash. The browser makers have killed Flash Player for some very valid reasons. Adobe didn't have much say in this. Flash content developers had 3+ years warning that this was coming.