One can only hope there'll be a watershed moment like the one that killed Digg. So far, reddit has been very careful raising the temperature so as to not scare the frog before it's dead.
I think a critical part of the Digg exodus was that most people already saw Reddit as a clear #2 in the space. When Digg fucked up, there was an obvious place for everyone to migrate to. I don't see that right now. Facebook isn't cool anymore, Twitter has a large number of people who won't use it because of Elon, Mastodon isn't mature enough to gain casual users.
Bascially, the problem I see is that if people leave reddit, there isn't an obvious place for them to go? TikTok maybe? I just don't see an Pepsi to Reddit's Coke.
Obviously Discord is chat focused so not a one-to-one replacement but I am not sure that the younger generations will care.
Plus there is the possibility of discord adding a Reddit/forum like feature, since they already have the mindshare.
Reddit is about discovering content. How would you discover anything on Discord? Is there a trending list to see the top messages? Is there a way to list Discord communities so you can discover ones matching your interest?
I'm at a lost to how the two are similar in any way except for the "young generations" use them both.