I alway believed that reddit needs a redesign, but now that I'm thinking it, Digg had 4 redesigns and maybe that is a part for why it failed. People don't like change.
When when the dreaded "V4" came, it wasn't the design that was the problem, it was the change to prioritising major media companies.
It would be possible for Reddit to change their design without changing functionality. But I suspect that no-one would be happy with the result.