As far as going in solo let us bring in personal FC retainer armies. That way, we can play as our parties FC or those who want a good venture can queue their retainers on DF and have a higher entrance for FC and will be great for me (and I'm sure many other players) who want to do it without the aggrivation of real players because they are annoying from time-to-time.
As far as a community aspect you can give rewards similar to tokens in Ravana and Bismark (EX) runs so we can choose what gear we want, new crafting gear for DF, undersized boost for those who wish to play it with others in a small group (8 - 16 players) & give experience for those at 50-60 realative to DF bonus.