The more things change, the more they stay the same. Despite HBS featuring the most publicized changing of the guard in admissions that I can remember, they are basically keeping their "open-ended" question style intact. In fact, more than keeping it intact, they have reverted to the more straight forward version they used in 2013 and 2014, rather than the more clever (but probably ultimately less effective) "introduction" prompt from last year.
And because they are staying in this lane, it means that my three thoughts need to stay in the same lane they have been in for years - because understanding the psychology behind this essay goes a long way to explaining how you might solve it.