Arsenal are the only Premier League representatives still in the UCL, they will also face opponents who have eliminated other EPL representatives (Liverpool and Aston Villa). Now the big hope is on Arsenal to win the trophy, but as you said, Arsenal will have a big challenge because PSG plays more collectively since Luis Enrique took over.
Now Arsenal just need one more win in the EPL to secure a place in the top 5, they have to give their all in the UCL because the EPL trophy is already Liverpool.
In this season, there is no top league in Europe with more than one reprepsentative in semi final of UEFA Champions League, Arsenal and Premier League are not exemptions. In this phase, four clubs from four leagues are fighting for two tickets to the final match and they are: Arsenal (Premier League), PSG (Ligue 1), Inter Milan (Serie A) and Barcelona (La Liga).
Arsenal will care more about themselves than Premier League and they will fight to win their matches, take a trophy that they have never won in history, than thinking of how to become a pride of Premier League. The same with PSG and those two clubs are direct competitors after they made some good impression in previous phases.