Let’s not forget age. Gundo is coming into his twilight, Bernie is still very young and versatile. There’s not only room for both today, but an opportunity for one tomorrow.The only ways to fit all 3 of them (Gundogan, Bernie, KdB) AND a striker like Haaland is to
1) Play him as a winger, but I think that neutralizes some of his strengths and Mahrez is better here, so I don't like this option.
2) Play him as a DM, but I think Rodri is better here due to his aerial presence and physicality.
3) Play 3421, and pair him with Rodri, basically this means he takes Cancelo's role when he plays next to Rodri. We have actually seen this in the Fulham game when Pep played Jesus, Aguero, Ferran up top, with Rodri and Bernie in the midfield. This path means we lose Cancelo's creativity, but is better than previous 2 imo.
Otherwise, false 9 is the only way to accomodate all 3, but then that means no Haaland.
Luckily rotation has to happen anyways, so I don't think its a big deal.