I hope its the Bob Barbas fight and not a new boss since i dont wanna know the trick to killing all the bosses before i even get play the game.
Its only 3 out of like how many bosses....I doubt they will spoil the entire game and I have this feeling there is more to the Poison boss fight than that & plus as long as they don't go in depth like they did the Poison boss fight (showing off the counter/parrying system and how the demon grapple affects the battle) and just do what they did with Bob fight at Gamescon just show off only 1 health bar & etc.....I just hope there is a lot of bosses and not any of that boss battle only mission (unless if its the final boss or something).
I'll list all the missions announced and indicate if there is a boss in them to show how many bosses there could be. This is only an educated guess and I'm using the standard of 20 missions.
Mission 1-Tutorial (Where Dante meets Kat and is recruited)
Mission 2-??? (Here Dante meets Vergil I assume and starts working for him)
Mission 3-??? (Somewhere between these 3 missions they can fit in like 2 boss fights and one of them be that....)
Mission 4-??? (gorilla hunter demon at the pier/carnival shown in the Captivate trailer)
Mission 5-???(The guy who was right about Vergil, Lilith and other stuff did mentioned a giant spider mini boss at church)
Mission 6-Boss(Poison)
Mission 7-Boss(Bob Barbas)
Mission 8-???(This mission could be where Kat gets kidnapped)
Mission 9-??? (Most preferably mission 9 or 10 is the Devil Dalliance mission and Lilith is most likely a boss here)
Mission 10-??? (But it could be mission 10 if it is in the middle of the game so says Alex Jones)
Mission 11 to 16-???(4-5 bosses can fit in here)
Mission 17-???(Unknown)
Mission 18-I'm guessing re-fight all the bosses
Mission 19-Boss(probably Mundus)
Mission 20-The Final Boss Fight
I'm just guessing. So like 12ish bosses.