As sad as it may sound, but i think without the huge worldwide allegation scandal in 93, any follow up album to Dangerous would have probably performed worse than HIStory did in the given situation. Like it or not, there was also a benefit from this gigantic 93 shit storm that reached out much further than just the music scene. When the new record was ready, there was a "Michael Jackson doing music again" buzz, that probably would not have been there to that extent without the epic drama before.
The one thing that killed HIStory in the USA was the HBO concert cancellation. Sony lost a lot of money with that, so they were not that keen on investing more into promotion (in the USA) after that.
Btw, HIStory is also counted as "the highest selling double album" i think.