Quick post to spread the word – mmo champion has videos of a DK who successfully completed Yogg+1 solo, straight after doing a solo kill Mimron on hard mode: Firefighter! Also in the post is a Malygos solo by a Warlock. So we have a Death Knight doing what they are darn good at, by demonstrating that Firefighter is nigh on impossible for some groups now, but plausible for a solo DK. That is great.
Then a Warlock stepping up and showing that it is not just plate wearers can solo old content. Malygos is a darn healthy fight. Just amazing efforts by both the Death Knight and the Warlock.