Maybe bronte knows the capability of the gang so he chose to trap them and get them killed in a ambush of his setting and he thinks let's settle this so no one from his guards die

Idea: what if the gang killed everyone during the party at Angelo Bronte’s mansion?

What if Dutch killed Bronte after the bank heist?

1;11the reason behind Cornwalls surprise visits was abigail

Can u do what if certain members of the gang didn’t die like Sean, Lenny, Hosea, kerin

In that situation, I see no possible realistic way that everybody from either side could survive it. The gunfight surely would not end until one side is completely wiped out. So, either all 3 gang members die, or Bronte and all his men die. 3:43 It was point-blank range, in a 10-foot square room, 3 gang members vs 4 Italians plus 1 unarmed Bronte, and no cover for anybody except maybe the Italians near the doorway. But those two guys were right next to Arthur, so I seriously doubt they'd even make it through the doorway anyhow. Definitely not both of them. The doorway isn't even big enough for both of them to get through it simultaneously. It isn't a stretch to imagine other Italians occupying the hallway either. Even if the gang wins that, they still gotta find Jack and it's almost a guarantee that at least one of them, if not all three, would be, at the very least, critically wounded if not dead. Dutch would have taken the first shot. Odds say Dutch gets killed since he had a shotgun pointed at him, and John gets killed having a shotgun and pistol trained on him. The fourth Italian wasn't aiming but did have his gun out and he would have shot Dutch standing right next to him. Arthur is in the best position only because nobody was aiming at him. Once Dutch pulled his guns, all four Italians probably would have turned their attention to him first. John & Arthur would not have weapons out until Dutch started shooting. Dutch was behind them so they could not see him draw and only get into it upon hearing shots. Maybe they can see his shadow draw I suppose. Either way, Dutch and John are gonna get shot, Dutch multiple times. I can see Arthur & maybe John coming out of it, but not Dutch, and not Bronte (sitting unarmed inches from John & Dutch and John very angry with him). And I reckon either John or Arthur or both get shot up pretty bad despite winning the shootout. Especially since they still have to clear out the mansion to get Jack too, most likely while seriously wounded. Also, there is the statement Arthur makes on the way in: "if we start shooting Jack will surely be killed." Had Dutch started shooting, it would have been a catastrophe for the gang either way. They either lose Dutch and Jack and probably John too then run home with lots of bullet wounds, or they never get out of there at all. Nobody is that bad of a shot. And there were four Italians in there. All four of them would have to be totally inept with a gun to miss every shot. But these were Bronte's most senior and trusted bodyguards. I see no possibility that Dutch makes it out of that room once he pulls his guns. Probably John too. Leaving Arthur alone against everyone, trapped upstairs, probably ending him as well. Especially after the cops started to show up there. Maybe he gets far enough to discover dead Jack. So, the rest of the story would certainly have been significantly different without Dutch there to lead everyone astray, and probably without John, Jack, and Arthur too. The most likely result, in my opinion, is Bronte and several of his men get killed before they manage to eliminate the gang members with the help of the cops. And they would have lost Jack as well. RDR1 would have to slip into a parallel universe.

honestly i think any outcome would've been super unrealistic considering it's 3 against like 100, and realistically bronte and his men would (probably) kill jack almost immediately, and any if not all of the 3 would die in the shootout, of course arthur is overpowered as hell in this universe but i just don't see how starting a shootout at that exact point when they visit his mansion could possibly have a good outcome that results in arthur, john, dutch, and jack all staying alive (especially considering if you played the first game you already know 3 of those 4 live)