99% of these mages play with druid, if druids get nerfed we'll see again.
This is not a satisfactory answer. While it has some truth to it, there is absolutely no way that's the whole story. Everyone is playing with a druid right now, druids are ridiculous. By that logic every class is fine right now because they're all playing mostly with druids.
If druids get nerfed and disc gets the help it needs, it'll just be mage/disc/X. Mage/druid/X is easily one of the strongest comps in the game right now, and rmd may be the actual strongest comp in the game. This is not because druids are overpowered. Mages are at fault here too, and are EASILY somewhere between strong and overpowered. Making any kind of buff to mages right now is going to be a terrible move, moderate buffs to an already strong class is exactly the type of thing that ends up tipping the scales and fucks up a whole season's ladder.