There's a difference between monetizing traffic and bastardizing content (though I'll be the first to admit I'm not readily familiar with Digg's community.)
I think there's still a pretty big niche to be filled with genuine high-quality news aggregation. Even if they were to nuke Digg and start anew, having that existing userbase is a big advantage.
Sortfolio has established itself as a market leader with a solid revenue model. Digg's revenue model is unclear and it is nowadays dwarfed by competition. That said, Betaworks knows what they're doing, so it's certainly got potential.
Compare this to 37signal's Sortfolio, which sold for $480,000 a few weeks back.