If there is no "stand in this and you will die" mechanic, I can go afk on a boss at 30% and not lose agro, maybe even sooner than that, threat is no longer a part of the game on boss fights
IT IS VENGEANCE THAT IS BROKEN BLIZZARD NOT THREAT! I simply cannot understand where you are trying to take your game right now. Some of the design choices you are making are clearly SCREAMING TO US! "all we want to do with WoW is make money and we no longer care about the minority" This is nothing new to those of us in top end raiding guilds, but we were the VERY VERY small minority, tanks are a major minority.
IMO, threat was only an issue when you had to move. If you had to move for 6 seconds, thats 4 globals. If you only manage 1 global while you are moving because of contact time, you will lose threat. Vengeance solved that, but it took it way to far. Vengeance needs to be a stopgap that allows you to hold threat while moving and not hitting the boss for 5 seconds out of a minute, not go afk at 30% like it allows you to do now.