Those are the standings as of now. By the time the group stage comes to an end, I expect Portugal to top the Group A (right now both Serbia and Portugal have 10 points from 4 matches, but Serbia is ahead as a result of better goal difference). If Portugal somehow misses the boat to Doha in 2022, then a lot of people will be disappointed. As you have correctly pointed out, it may be the last world cup appearance for Cristiano Ronaldo. He's already 36 years old and I don't think that he will continue playing until 2026.
Yes, World Cup 2022, it should really be the last world championship that Ronaldo will participate in. But I think he should still participate in the 2024 European Championships.
So, let's see Ronaldo giving everything he has to the team to perform well.
We still don't know it yet. And I don't think that Ronaldo has decided when to end his national team career. I expect him to play football until the age of 40 at least. If he doesn't retire from the national team before, then we can see him in the next European Championship also. And Ronaldo is still very strong and energetic. He is still very determined. And as long as he is in a good shape, he should be able to play until being 40 at least.