There was a multi-boxer raided up to nax in vanilla as 4 mages and a priest...
now he still had smart macros so mixed classes weren’t a problem...

personally i plan to raid with 2locks, 2mages and a resto shaman where my mages /locks are one button spam for dps and my shammy will be using grid and clique... I can’t foresee a problem for Molten core (Geddon being the only difficult attention wise and the knock backs from Raggy being the other)), Bwl razorgore could be painful.. AQ40 c’thun would be a no go... and nax would be semi possible, your issue will be the willingness of your guild to bend around you. I mean they will have to replace your toons with actual people for some fights and I don’t think the replacements will like being benched for what they see as someone who can only operate at about 80-90% at best