Michael Jackson is the second-most recognizable artist/group of all time, standing neck-and-neck with The Beatles. Unfortunately, much of this attention is based more in questioning his personal life than admiring his oftentimes brilliant musical output. Because of this, I again encounter the problem of a topic covered once too many, so I'm not going to waste time with a summary of what everyone knows. Instead, I'm going to focus on Jackson's significance in my overall flowchart of pop music.
I've mentioned earlier that The Beatles represented a divisive moment in pop history. There is pre-Beatles pop (crooners, vocal jazz, rockabilly, and rock and roll) and post-Beatles pop (what we understand as classic rock, blue-eyed soul [also popularized by Roy Orbison], and psychedelic rock). In the same way, there is pre-Jackson pop (disco, New Wave, synthpop) and post-Jackson pop (contemporary R&B, neo-soul, R&B, new jack swing, modern dance music). Both groups were important in how they combined the elements that came before them into what came after them; you could consider the two groups as bottlenecks in simplified schematics of pop music (note that this excludes metal, punk, and goth, which are basically small sub-groups of the mainstream).
In radio terms, Michael Jackson brought about both the end and beginning of classic rock. Before Jackson and the pop music of the late 80s (think Madonna), classic rock existed as AOR stations (previously discussed in the Roy Orbison post), which played the same basic music but with a slightly larger setlist. The name change, I suspect, was due to a shift in perspective; before Michael Jackson, AOR still existed on the fringes of pop music. Artists fitting into the genre were still accumulating (and would continue to do so through the end of the decade, albeit at a slower pace) and were exhibiting influences from the rest of the pop spectrum (AOR + synthpop = Steve Perry's Journey, for example). After Michael Jackson, pop music consolidated/collapsed around him and R&B as a whole, leaving AOR in limbo. AOR was no longer pop, but there was still some demand for it. Therefore, canny corporations created classic rock, and DJs perpetuated it.
This was the last major divisive moment of pop history. Modern pop (contemporary R&B) carries the indelible mark of Michael Jackson, and will continue to do so until the next breath of fresh air comes along. My guess? Synthrock.