(Note: Quick shoutout to Dreamweaver 6.0 which was a power, WYSIWYG editor. Today, things like Pinegrow might fill the niche.)
It's death as a hugely-popular tool was largely due to Apple and Adobe. SaaS model isn't helping it far as wide adoption goes. It also got popular through piracy which hints the replacement should be profitable and widely deployed like open source.
I think this might be a good opportunity for a license like PolyForm Non-Commercial. Free users either can't commercialize their content or, like CompCert Compiler, must make the outputs GPL'd (or AGPL'd). The Flash replacement would have a fair, one-time price for unrestricted use with source or you share like they shared with you. What do you all think?