The Silence of the Lambs/WMG

Manhunter takes place in a separate continuity from all the other books and films.
Chilton isn't a dick. Dollarhyde. Hannibal's victims were co-eds who happened to be his patients. His last name isn't even spelled the same (Lecktor). Heck, the Manhunter Lecktor might not even have been a cannibal at all.
 * More or less Word of God, seeing as there exists a film of Red Dragon, clearly tied to the other films.

Lady Murasaki is still alive
And is waiting for a chance to do what she should have done years ago: kill Hannibal. If there is another book, there will be an epic fight scene in which she faces off against Lector with the Murasaki family katana.
 * Won't she be a bit... elderly to swordfight? Since she was (according to my superb calculations) thirtyish during The Fifties, she will be a bit geriatric when coming to seek revenge, Japanese or not.
 * (OP) There are many instances of octogenarian martial artists who can still kick serious ass. Being that by that time, Hannibal will be no spring chicken himself, it might not be as one-sided a fight as you think.
 * An addition to the theory, if there's a fifth book, that's what will happen..., but Hannibal would still win because there's no way Harris would allow the object of his mancrush to lose.