when people catch wind that pvp intensity/crediblity will only hold validity in DF it will attract them for that reason. people who play wow for the arenas will come to DF, people who play to raid will stay there because they want to see the warcraft I-III storyline played out.
carebears will come to DF because their mobs will have better AI than any other MMO, mobs at range will use ranged weapons/spells until they get close quarters then use mellee, they can climb, flank, use teamwork, push, raid player cities, migrate because they're being camped too much, become extinct, send runners to get support from allied tribes/clans/whatever, build their own social environment starting from campfire to full fledged embattlement forts on the outskirts of nearby player cities...all while having to strategically fight these mobs while watching their asses for PK's.
people heavily into crafting will like this game because of the softcap, a hardcore carebear basketweaver will be able to be a highly recognized economic superpower if he has the most blueprints for items, from the really tough mobs who drop them, and most of his softcap will go into crafting which not everyone is going to do...most PK mule crafters won't compare in 4-6 months compared to a crafter main char. the resources for the rarest items (racial items and high quality magic items) will be in bottlenecks, coves, and dungeons and highly contested....while common crafting resources will be all over the place for PK's to farm farmers to get their skill up on their mules to where there'll be a lot of 'average' crafters who can supply people with the essentials to go out and PK/get money for higher quality gear. the only items you get aside from looting/crafting will be shit you can buy from NPC's or get from quests and are going to cost hardly anything, and only be worth while if you have absolutely nothing else and have to kill rats bare handed in order to get them...so the entire economy will be playerbased which will attract a lot of eve economy whores.
there will be a huge market for solo players just as much as siege oriented guilds. with the lack of convenience in instant travel (reagents for instant travel single/group will be extremely high priced, and difficult to acquire [rare]) the solo player PK or "adventurer" will be able to walk around in the fucking forrest for ages and either evade fights, or gank the fuck out of grinders, or pick targets to kill...plenty of shit to do without ever participating in a siege, although the solo player getting in on a sieges loot benefits, and smaller guilds will be able to attempt to capitalize when it gets crunch time and the city is "up for grabs" to yank it out from the offending guild.
roleplayer carebears will love this game because they have an evil aligned faction set (orks/mahirim), against the world faction (alfar), and the traditional carebear coalition (humans/elves/dorfs).
glowy carebears will have an attraction to this game because there will be gear that isn't obtained by everyone, like racial weapons and the highest quality armors. they even have elemental weapons which basically look like a hilt with lightning and shit coming out of them (speculation says they will do elemental damage and effect different types of resists you can raise like Magic Resist in UO, but instead of one blanket resist you will have multiple types).
FPS players may get interested in this game because the dungeons are described by devs to be like counterstrike levels, but obviously with midievil dungeon setting..plenty of room for ambush etc by other players while you try to find/kill bosses within as well as the 'trash mobs'. and stating the obvious FP casting/archery.
sim city / RTS side will be attracted to city developement which will be more complex than ever seen in any MMO, or RTS for that matter.
when DF comes out, there just isn't going to be any games that will compare on any of the previous levels as far as MMO's go. the only people who will not be interested in the game will be people who just flat out don't like PvP in any format what-so-ever. it's not about what they'll settle for, or try to negotiate, they just won't do it regardless. part time PvPers will become full time PvPers and enjoy everything about it. the people who will quit this game will be people who aren't coordinated enough to rapidly swap between FPS casting/archery and mellee fluidly, and people who don't use hotkeys/macros and need to click all of their abilities/spells. there's a whole new market of people out there and a ton of people added to the different types of demographics because computers are so much more available to different classes of people now, as well as high speed internet. imo WoWs success was a timing issue, it released as the most current, and user friendly graphically pleasing MMO in market. noob bootcamp is over, people are familiar with MMORPG structure and are looking for more dimension to what they're dumping hours and hours a week into. people are tired of having 15% of their guild being compitent and having to deal with noobs with decent gear who never do shit right on raids, there are people who only log in on raid days to try to get some bullshit three times a week and do arenas the rest.
there is no question that UO is the staple MMO pioneer regardless of it being the first or not. previous MMO's didn't matter, UO was the first widely popular competitive MMO. the vast majority, if not the entire playerbase of WoW has heard of UO by now, stories in vent from a few guildies being nostalgic or whatever. this is the first game that is structurally being designed to resemble the same pressure, risk, and intensity that UO provided on levels for every demographic of player. there will be fucking MASSES of people trying this game out at the least. people will stay because it provides more challenge than they will have ever experienced previous. people will leave because they're bad at the game, not because of the consequences.