As a Paly I was able to DPS/Tank/Heal while I went from 1 - 62ish no matter what my spec. Once I got into Outland it was tougher and trying to heal from a tank spec, while technically possible was just getting stupid to waste people's time...
Is it the same for Druids?
Can I tank anything through Vanilla content while spec'ing Cat, Caster, or healer?
Same question for healing instances while specing Bear, Cat, or Caster?