Warrior is best when you are low geared and progressing vs bosses you don't have the gear for. Best early on. Also has great tanking CDs to deal with hard hitting mechanics/enrage timers. Poor aoe threat and their single target threat is good early game then gets worse as it doesn't scale well.
Paladin is the good ole AoE threat tank. Hard to gear early then turns into a mega beast as the game goes on. Reliant on having mana.
Druids are solid early game and are like warriors with pretty meh aoe threat. They scale super hard threat wise as the game goes on and become the best threat tank by sunwell. Its generally an OT because it can wear its DPS gear and its DPS talents are something like 2 or 3 talents different than their tank build. A warrior OT is ass because he does useless damage once his target is dead and a paladin is okay because he can off heal when his target is dead but a druid can go cat form and pull decent DPS numbers when his target dies.
Its entirely possible if the TBC release is as easy as classic was that prot warriors might be pushed out of the meta if bosses don't hit hard. On tbc private servers bosses have millions more hp and are tuned to slap hard to make fights interesting so a warrior MT is generally the most accepted in the scene. A fury or a arms warrior can keep up demo, thunderclap and allow a rogue to expose armor for more DPS while keeping the boss debuffs.
As for the fury statement they aren't as awful as people make them out to be. If warlocks/hunters are an S tier and boomkins are a D tier fury is somewhere around a low B- in terms of raw DPS. Same with rogue, they do respectable damage but they don't bring an ass load of utility like an enhance shaman. An arms warrior is somewhere in the C category and he boosts DPS of all physical dps by 4% which usually beats out a fury warrior by a little bit in the end and like rogue you can get what little utility the class offers with just 1 of it. If you have an arms warrior already you may as well take another hunter or warlock instead of a fury warrior