I agree, it has to be the next fight.
I mean like the GSP thing mentioned above, I'm all for that big time but not before the Tony fight, Tony is fighting for the title and has earned this a long time ago so it has to happened.
GSP isn't an active fighter so that's more like a one off kinda fight outside of all this, it's all part of seeing if Khabib is the GOAT too, which Khabib has even said himself he isn't until he's beat a few more etc..
The GSP thing can happen after, specially if Tony happens to lose then we can go for that I reckon