I haven't seen Canelo doing that against a boxer who specializes in boxing at a distance like BJS (Floyd or Lara). He certainly adapted in fighting GGG. He actually brought a relative efficient tactical plan to box GGG and move in the long distance. In my opinion, this strategy yielded the well balance fight we observed... I can't say with confidence what the likely outcome would have been if Canelo decided going toe2toe against GGG...
However, that worked against GGG because employing such tactical plan against a pressure fighter is the most intelligent way of neutralizing his offensive. But the return such plan against an stylish is counterintuitive at best. So, the most logical thing for me to expect is seeing Canelo pursuing and pressuring BJS all night long, shooting heavy-artillery punches that effectively, after multiple swinging-and-missing, may just lower the temperature of the entire arena.
Now, I would agree that not too long ago, BJS would not have been able to handle GGG, but based on recent performance, that's no longer the case...
Needless to say, this is all speculation... I might be dead wrong, you may be correct... vice versa.