Reddit was an alternative Digg for them to flee to. I’m not sure what an alternative reddit is. What’s more, the scale of Reddit today blows Digg, in its heyday, completely out of the water. So any transition would take much longer. There’s just too many niche subreddits where they people wouldn’t know where to go. It’s similar to how Facebook has a vice-grip on people because everyone seems to have one group or community that puts notices on the group page.