Which odds will go down? PSG or Chelsea? If PSG I think the odds will remain the same more than 1.5 because if it is below that it will make bettors choose PSG because it has a very convincing chance of winning, with odds of more than 1.5 it will make bettors a little confused because as you said nothing is impossible in football anything can happen even clubs that are considered weaker can provide surprises so we can't underestimate Chelsea because Chelsea has also fought so far they have been much better this season.
You're right, at this point bet companies are also care let's not forget that of them are also gamblers, they really understand that some people might decide on what to bet today that the match is taking place, the old dropping or rising of a thing in this kind of match is something they will want to be very smart about, despite many people believe that PSG may likely win, there are still bettors that don't believe that it will be easy like that, in the game of soccer, drawing conclusion especially when we know the history of both opponents doesn't really make sense, I love the points you made here, it shows that you're a football enthusiasts and you have been following the recent events that has been happening in this competition.