Someone will solve it and replace reddit in at least some profound ways.
Doubtful. These are deep-seated patterns that have been playing out in online communities for decades, and every "oh we'll just build a new thing that won't have that problem" attempt has... had the same problems.
For examples, and some interesting thoughts on the issue, start here:
Well, fundamentally, we've been designing online communities in the same (flawed) manner for decades. This is basically the recipe for reversion to the mean:
1. Allow any user to add themselves into the community; and then,
2. allow the course of discussion to be set by majority rule.
The site (or subreddit, or newsgroup, or whatever)'s focus and usefulness will gradually disintegrate as people in secondary demographics join (e.g. for programming, people interested in web design) and then tertiary demographics join who are only interested in things the secondary demographics like, and actually don't care about the original, primary focus of the community at all.
For examples of tertiary-demographic takeover, see Reddit's /r/music and /r/movies. The primary demographic wanted media discussion; the secondary demographic wanted to discuss specific pieces of media; and the tertiary demographic just wanted links to new media they hadn't heard of. (Which—for /r/music at least—when combined with the average new-Internet-user's set of "music they've heard of", the way people have a more positive association with music they've heard before, and the way democratic interest floats up the most agreeable items, the front page becomes basically "Reddit's Top-40 chart.")
Any community that avoids this will fundamentally have to avoid doing either #1 or #2.
This sounds pretty easy to avoid by moderating to keep focus and prevent drifting. "This subreddit is for media discussion only. Irrelevant links will be banned."
I think the question is whether there's any way to do this without moderation, because moderation doesn't scale. (Community-based moderation might work, if you could trust the average user to moderate right. Now you have two problems.)
