Arsenal may not facing Barca and Munchen in Group stage, but they still will face PSG. PSG Still strong without Ibrahimovic. And it still hard to beat them.
PSG is strong sure but last game they mess up lost but this is happening cuz they still raising form and team is not fully set up i believe they will manage this season fine
PSG might be still the strongest team on Ligue 1 even without ibrahimovic but in European Competition (Champions League), I doubt they can do something better than what they did last year.
Lucky them that they are in a easy group, maybe they can pass the group stage on 2nd position under Arsenal.
What made you think that Arsenal can stay above Paris Saint Germain. Missing Ibrahimovic are not really a big deal for them. In fact , they have won 7 times in 8 matches ( including preason game ) and a lose which they got in last weekend against Monaco , shit happen sometimes , still not a big deal. They already get some good signing to fulfill the lost of Ibrahimovic , especially Ben Arfa and Jese Rodriguez.
You should really doubt about Arsenal because PSG always goes further than them in recent UCL.