Fight or be the main ones responsible for the downfall of guys with bounties that high? Who's Who might have a bounty that high but it's doubtful (considering Jimbei's bounty despite all that he's done and also considering Ace's bounty was 550 and Luffy's after beating Doffy was just 500). If Sasaki has one that high then I agree that Franky will take down a guy with a bounty that high but I don't see Sasaki reaching that high.
I'd say Chopper is capable of helping but Marco literally had to hold down Queen and that's the thing. I don't think the scene was meant to be Chopper fighting him on par. He neutralised the threat of the virus and the hit on Queen was basically meant to wrap up the payback he got against Queen and earn him respect from the alliance. I don't see him actually facing Queen without Marco, Drake or Sanji doing a good chunk of the work. I want the characters to fight opponents somewhere around their level so they progress at a reasonable-ish rate. Chopper can face the Numbers or help against Perospero or a Flying Six but I don't want Kaido's number 2 taking anymore damage from Chopper.
I think if the Straw Hats' current opponents have bounties that high then sure but I don't want them beating guys they have no business defeating.