The various permutations still favor Lando, as any podium position will secure him the title.
If Max wins, Lando has to finish off the podium for Max to be WDC.
Piastri has to win, period, and he has to have Lando finish sixth or lower to be WDC.
So the "nightmare scenario" for McLaren is on the final lap Max is going to win, Oscar is third and Lando is fourth. In such a situation, I do expect the team to order Oscar to cede third position to Lando and I expect Oscar to do so so Lando can win the WDC.
If he does not, he is going to seriously hurt himself within the team. Management have stated that if you cannot play by "Papaya Rules" then you have no place in the team (and in this situation, I believe such rules say if you cannot be WDC, you ensure your teammate is) and I expect a majority of the team's staff support Lando more than Oscar and if Oscar scuttles Lando's WDC, that is going to generate resentment over the winter break.