I think Facebook is experiencing a similar thing. A frustrating amount of my network has quit, which makes planning events more difficult (and is frustrating). The difference for Facebook is that they have enough money to just buy wherever people move to. Reddit doesn’t have that.
At this point I think a lot of people are actively looking for (and probably finding) replacements. I’m actually surprised Reddit still makes their public api so easily available without any keys. I wonder how long until somebody just scrapes the content and uses that to help get over the network problem and start a competitor.