Salzburg can still be targeted by Real Madrid for 3 important points that will help them maintain their automatic qualifying position. If they win over Salzburg, then Real Madrid's points will be 12 which will be able to maintain their survival even though they have to fight through the playoff zone.
In order to qualify for the next round even though there are two more matches left, I feel that they can qualify for the last 16 even though Brest is an opponent that can be considered tough considering their achievements during their six matches in the Champions League.
Yes you are right. Salzburg will definitely be targeted by Real Madrid and with the current situation of Real Madrid on the Champions League standings, I’m sure they will be able to comfortably get all three points against Salzburg. And talks about Brest being considered a tough opponent for Real Madrid is unrealistic. No matter the condition Real Madrid may be presently in the Champions League, I believe Real Madrid can comfortably win Brest with even their second team.