The thing is, the number of people who want to regularly visit a site that looks like it was made in 1998 and mostly comments on decade-old inside jokes and features an increasingly libertarian slant is not growing because the number of people who fall into that category is not growing. Slashdot has four options:
1) Figure out how to grow their customer base without eliminating their existing customers (difficult; existing customers oppose change and tend to either directly be, or through their opinions appear to be, hostile to newcomers),
2) They should give up growing their customer base and just be the best they can for their existing base, trying to win back the Soylent News crowd. (This might work, but wouldn't grow the base. They'd be like "classic rock" stations or "oldies" stations before that, who were playing popular music when they started, but rather than keep up with pop they decide to freeze in time and mostly ride the same fan base to their mutual deaths. Plus this assumes the existing base was homogenous; it wasn't, and as some groups have gotten more vocal they have permanently chased others away.)
3) They could say "fuck it" to their existing customer base, make all the radical changes they want to make, and start over rebuilding a new crowd. (This usually doesn't make corporate overlords happy unless it's their brainchild idea, e.g. Napster, etc., and even then it rarely works.)
4) Cowboy Neal could pull the plug and shut the whole thing down. (I needed to include a decade-old inside joke here somewhere.)