Do you think Catholics would willingly add or drops books today if Bergoglio decided to adjust the canon?
Absolutely. Without question.
And all the more if he spoke ex cathedra.
And it would matter not if it contradicted previous teachings or doctrine. By some mental gymnastics known only to someone deceived by a cult, they could rationalize it and then come to accept it as truth and continue to exclaim that Catholic teaching has never changed over the last 2,000 years.
Excellent question! If he got together a Council and persuaded a majority of the magesterium to agree with him and then made an "official" ex cathedra pronouncement, then "faithful" Catholics really have no choice in the matter - they HAVE TO accept it.