It really depends on what you mean.
There are going to be a lot of fury warriors coming from guilds that had 8-12 of them in their guilds that will suddenly realize their guild only needs 1-3 total warriors, and there is a strong chance none of those 3 will be fury. So they are going to have to cope with that, they will ether get lucky and be that 1 fury warrior in the raid, 2 go protection and be a MT/OT, or 3 be the arms guy. The rest are probably going to have to consider rerolling.
When it comes to niche specs, there will only be a real demand for 1 moonkin, 1 ele shaman, 1 (sometimes 2 for progression) shadow priest(s) 1 ret paladin, 1 rogue ECT.
There will be guilds that will absolutely run more than one of each of those, but they are looking to bring players and not be optimal, the numbers presented are rough outlines. Can guilds get away with 2 melee groups filled with fury warriors and ret paladins? Sure, but it is more of a thing to work around to fit people in, than have in a typical raid.
A typical TBC raid composition and I do mean typical. Looks something like this:
1 warlock group with an ele shaman and moonkin
1 Hunter group with an enhance shaman
1 healer group
1 melee group with an enhance shaman and an arms warrior
1 tank group with the tanks a resto shaman for windfury and overflow.
there will be some guilds that run different set ups than that, but that is one of the more consistent ones what they plug into every slot is going to depend on what they have in their guild, but the raid comp I posted is very typical.
What your guild brings is going to rely on what tanks they have as a foundation to the raid, if they bring 1 prot paladin, and 1 feral druid as their 2 main tanks, what they fill the raid out with is probably going to be different than having 2 prot warriors as main tanks. Running a rogue with expose armor becomes more more appealing to raid leaders if there is not a prot warrior as an example. They will probably run an extra warrior forgoing expose armor and have sunders stacked faster, as well as have a fury warrior that can be that flex tank/DPS on specific fights.
Your question is multifaceted and will revolve around what raids do, the standard raid comps that people build for TBC classic, will trickle down to what happens later on in 5 mans and 10 mans.
But I am sure there are guys that are like “my guild ran with whoever was online and we had 25 druid raids and we just battle rezed our way though illidan and it was not hard” and will tell you that it doesn’t matter what you play and just play what you want and you can do the content with whatever. Leaving out the fact that the guild is more than what their guild does and things will be more difficult for some classes to find 5 man heroic or 10 man spots, as an example.