As far as Mega Man 1 and 2 goes, MM2 specifically said 200X. However, some of the subsequent games said 20XX. Still, that can't be too far into the future compared to MM2.
Did anybody else think 200X and stuff like that didn't refer to years as we commonly refer to them back when you were younger?? I always thought 200X in MM2 stood for something like After Colony (AC) 195 in Gundam Wing or UC (Universal Century) 0079 in the UC Gundam timeline. Like, it was so far into the future, a new year system was created.