12 years and counting... I cannot see another undisputed heavyweight champ for at least another 2 years. Will there ever be another? Does he next one need to also unify the WBO? What a mess...
It was a total of 5 months minus a day wasn't it? And his last multi belt reign about 2½ years. It's a guess how long it takes for someone top get undisputed again, because it's much more up to politics and bravery of the individual beltholders and promoters as it is up to a single top notch fighter. You can be so much better as the rest, and you still might never even get your hands on 2 major belts, just because the others know you're so much better.
There was no question that Lennox was undisputed, Wlad was even then still considered an up and coming prospect/contender.
Vitali at the time actually, but I get your opinion. He was seen as undisputed though at the time, no matter how short it was.
Then by your criteria there has never been an undisputed champion since the WBO belt was created in 1988. No heavyweight since 88 has held all 4 titles at once.