If Bagnaia can get back to the run/form he had before the Japan Grand Prix, the 18 points won't be much, that's true, but let's wait and see if he has the nerve to do it, he knows it's all about the World Championship title again like last year when he crashed. If he finds the lightness and finishes first in Thailand, it will be difficult for Fabio.
That's why the competition will still be fun to watch because there are 100 more points still up for grabs by all the riders at this point including Bagnaia and Quartararo starting from Thailand this week. Because both will try to finish in the highest rank in the remaining races, because finishing on the second and third podiums is not necessarily safe for both of them if one of them is on the first podium.
I don't think there will be a stable order from Ducati in the next 2 races, which I could imagine, if Bagnaia is behind Miller, Miller won't really spread himself, Miller has said he wants to help Bagnaia and Ducati.
Miller really loves Bagnaia even though this year is his last year on the Ducati team because next year Miller will go to the KTM team. And I also don't think that another Ducati rider (independent team) will help Bagnaia in winning the world title although Ducati would be very happy if their satellite team is willing to help Bagnaia in this.