This is being a serious problem right now in the Castle Nathria raid. My guild, like many other guilds, has realized that we have way too many melee. There are a lot of fights where you have to run away from the boss for awhile and stand around and this is awful for melee and perfectly fine for ranged. We aren't melee heavy in theory - our damage is split roughly even melee/ranged - but that split is terrible for the raid we are doing.
It doesn't hurt that most of the top damage dealers in terms of raw numbers are ranged, so a melee has to be exceptional to get a spot even on fights where they aren't unduly punished.
I am playing a melee character.
I am not super worried about being booted from the raid team because I am the top damage dealer for the raid about half the time and always finish top 4. They are going to keep me around because at our level you still see large variance in performance within a spec, and I consistently deliver.
But the other melee players are probably feeling worried, and their worry is justified.
I don't have any good answers for them either. Swapping classes to a ranged class is possible, but catching back up isn't fast and most people don't want to swap. If we can't win with the composition we have then management is faced with the terrible prospect of recruiting ranged players and booting melee players, including people who have been around awhile.
No easy answers.
This is also going to compound the problem I talked about last time. This xpac has no infinite grind to increase player power. That feels good in a way, because we don't feel obligated to grind. However, it has the issue that guilds like mine are in bad shape. We have good players, but we will probably need some kind of slow power gain to actually beat the entire raid. It is made worse by the fact that we have what should be a normal mix of melee and ranged, but is bad right now. Top guilds just force people to reroll or recruit whoever they need. We don't do that.
I was looking into some options for how I could fix this by respeccing out of a melee role. I don't want to play a holy paladin healer, as I haven't done that in most of a decade. That would have helped us a little. I investigated playing a prot paladin healer and I think it might actually be pretty good. Nobody in top guilds is running a tank spec player doing full heals, but I always look for these weird spots to shine and I am a believer that this could be a good strategy.
Protection paladins have good throughput. My main heal is one I build up by attacking, and then BOOM it drops a huge heal. I can hit it about every 5 seconds for 21500 healing (if I am targetting someone at half health), which also puts a 4000 point shield on me. 4000 healing/sec is not enough to be a proper healer, especially because I don't bring big raidwide healing cooldowns. However, being essentially invincible, healing for 4000/sec, and also delivering 2000 damage/sec is a good set of things to do. I also have the advantage that if a tank ever dies I just step in and start tanking no problem. I am slightly squishier in my weird healing spec but only slightly, so me stepping in to tank for strategy (or to recover from calamity) is a fine thing.
Mostly people don't want me to try weird stuff like this. They go with what normal raid groups do. However, I think in this case it would actually be quite strong in many fights. Sometimes you need exactly 4 healers to get through a fight, in which case this build of mine is bad, but sometimes you need 4.5 healers and I can be an excellent .5 of a healer.
So far nobody has decided that we need to get rid of melee badly enough to get me to heal as a tank. I can't decide if I should wish that it would get that bad so I can try my crazy thing, or if I should wish that things just work.