Here's how it goes:
Ferguson gets injured and pulls out.
Lee misses weight.
Khabib pulls out to fast...then ironically misses weight after fasting.
Konor Mcgregor pulls out to go on post-paternity leave.
Konor McGregor pulls out again for a court date.
Konor McGregor pulls out again to try to improve his 0-1 boxing record.
Konor McGregor pulls out again because the UFC won't pay him enough.
Porier and Gaethje both fight and then go on 2 year medical suspensions.
Barboza pulls out due to living death.
Alvarez pulls out to wait for a money fight.
Artem Lobov shows up and finds out he's not part of the tournament.
Al Iaquinta ends up fighting Chiesa for the belt.
Nobody's sure if McGregor's, Ferguson's, or Khabib's belts are stripped or not. Dana White says none of them are stripped....but Iaquinta and Chiesa are 100% fighting for the real belt.
In a strange twist of events the real belt turns out to just be a temporary placeholder until Ferguson can defend his interim belt.