Fun Fact: It's never said what happens to the original Megaman in the X series. Only that X is a new, separate design (think younger brother) who awakens a century or two after Dr. Light's death.
Fact 1: In the Mega Man games for the original GameBoy, the green Mega Man Killer (MMK), Quint (short for Quintet) is actually Mega Man from the future. The present Dr. Wily made a time machine and visited his future self, who had given up his ambitions for world domination. In that time period, all was peaceful; so Mega Man had asked Dr. Light to remodel him back into his original self, and became simple lab assistant, Rock, once more. The present Wily convinced the future Wily to capture future Rock and make him his own robot, since he was defenseless. Future Wily sent his new servant, Quint, into the past to destroy Mega Man. Although Mega Man defeats Quint, the green robot flees, and hasn't been seen since.
So no: Classic Mega Man has yet to find an ending because of these events.
Fun Fact 2: in the X series it's never figured out just what makes X tick even during the Zero series set centuries after X.
But X sure is the best Cyber-Elf around, even after his body is destroyed!
Fun Fact 3: the X series was meant to end after 5.
Fact 2: X6 was made and translated that very same year, without Inafune's permission. The enemy placement and stage designs were poor, coupled by the random stage areas and just as random crippling status effects; that the game is considered extremely unpredictable at best. Icons warning you of danger in a certain level don't actually mean anything at all, so there might or might not be any problems there. Randomizing rooms that hold pieces of X's armor caused certain levels to have to be replayed multiple times for completion.
Fun fact 4: Zero was not only created by Dr. Light's nemesis, Dr. Willy, but is also the source of the 'maverick virus' that plagues the entire X series.
His design too is also never fully grasped making him and X the most powerful robots of their series & ages in terms of potential.
Fact 3: The pod that Zero was housed in when he is awoken kept him from spreading the virus and going berserk. When he fights Sigma, the Maverick Hunter contracts the virus after breaking Zero's helmet's gem; which is why he is affected so seriously by it throughout the series.
Theory: Supposedly the Maverick Virus (and subsequent Zero Virus) are products of Wily's research on the Dark Energy from Mega Man 8. Supposedly Wily kept samples and created Roboenza (Mega Man 10) as a sort've "tester," and he perfected it afterwards. Infecting Zero, who he had created to counter Dr. Light's Variable X project (just X), he found Zero to be immune but unstable, so he sealed him in a secret lab alongside the virus. (Just the big theory)
But damn it ZX was great. TuT if only it all hadn't gone south at Capcom, it would've continued.
My favorite series is Battle Network. The character designs are great; for both humans AND NetNavis. Hub Hikari is also the youngest Mega Man (11) other than Rock's suggested age (8).