It may be known to his friends but he might have family/relatives that he doesn't want to include into this yet. Coming out and feeling ready to come out is extremely personal, so whether that person feels ready to do it officially has little to do with how many people already know/guess the situation. It took Dan&Phil a decade to come out to their fanbase. I don't think Mark has an obligation or a deadline to do so because he's been vague about it or because people have assumptions.