The main reason you don't just change a game upside down is, your audience has already been "naturally selected". The players who stick around and play right now do so because they like the game how it is. Any poll you make talking about major changes like some of those mentioned is necessarily going to end up with a vast majority of "keep the game as it is!"
You can change a game upside down, but prepare for risky times because the audience is gonna shift heavily and be "naturally selected" again from almost scratch. Sooo, what should be done in this case is bring A LOT more people than the current amount of monthly new comers. (because if you don't, you're going to have a smaller audience in the end)
So I guess, with good enough advertising and marketing, and with changes planned well enough, you could do anything to DF. Except for the issue of long time players who were loyal to DF and AE and will feel screwed. If respecting your current player base is important, the only thing to do is then to keep DF as is and build a new game.
(developing PvP and guilds isn't major change technically, it's long planned features that keep being pushing back and back. players who don't like PvP nor guilds won't mind if they're developed, though they might mind that there are fewer storyline releases during those times)
< Message edited by Delgadoss -- 9/7/2011 12:38:10 >