It's a shame that they can't transition it to a read-only archive type site, where everything is still accessible and playable- jut no new updates or content.
That's what kongregate did I believe. They disabled the forums, the chats, no new games, no new achievements and that's it. It's a strange sensation to enter kongregate which had such a thriving community and see everything so... static
Literally nothing? Just leave it as is. There is a browser extension called Ruffle that lets you play older (AS2) Flash games, and eventually it will support newer (AS3) Flash games too.
Edit: most users won't have the Ruffle extension, so the one great thing they could do is add it to the site with a single <script> tag :)
Flash games are static content (except for high scores). A Flash game is just a SWF file, typically a couple MB (or KB!).
If you'd like to experience the games that were available on Miniclip back in the day, your best bet is FlashPoint, a big offline archive of Flash games (ships with integrated FlashPlayer and a nice UI to search for games).