The LFR problem would be pretty much solved if you made everything solo tankable in LFR. If the "real" raid has a tank swap debuff where tanks need to swap before stack number 5 or go splat, just make the debuff cap at 3 so one tank can handle the fight. If the fight has adds, just remove some and make the ones you keep do so little damage that the DPS can zerg them down (and perhaps remove healing aggro from LFR). If the fight has two bosses, have an immortal NPC tank show up and hold one boss for the whole fight in a scripted location.
Nobody in their right mind wants to deal with "tank swap at moment X or wipe" mechanics with some random LFR pug who may or may not be an idiot, who may or may not speak English, who may or may not speak at all... just remove the need to co-operate with another tank and tanks will be in the same position as DPS and healers who don't have to worry about half the raid having no clue whatsoever.