There is no reason to remove the Black Prince quest line (and thus the ability to get the legendary cloak that is a reward of that quest) from the Mists of Pandaria expansion of World of Warcraft as no drastic changes have been announced that would necessitate it's removal. The decision to do this is decidedly unjust to newer, some returning, and even future suscribers as they will never be able to experience this rather expansive content ... ever.

To add insult to injury, the announcement of the pending removal of the quest line was made at practically the 11th hour given that time this questly can take even with the recently-provided community buffs in place. Even those players that are part-way through the quest may be pressed for time to finish it before its slated removal date as not everyone can devote the time necessary to do so week after week (some may be unaware of it's removal to-date and may not find out until it is too late).

This removal would be understandable if there was going to be a dramatic shift in the world (like there was in the Cataclysm expansion) and there was going to be some cataclysmic event in Pandaria such no reasonible amount of tweaking would allow the quest line to fit in with the rest of the expansion anymore. However, nothing of the sort has been announced. The only minor justification put forth is the announcment that valor points were to be removed as a curriency, but there is no need to remove a whole quest chain for this, only to remove or modify one quest from the overall chain.

In summation, I and the undersigened are customers in good standing with Blizzard Entertainment, Inc. (and possibly other similiarly concerned parties) which vehemently protest this removal of content and request that you instead take a more measured and rational approach that involves the overall retention of the afformentioned content in the game much like every other quest line that is tied to piece of legendary equipment that exists to-date.