Arsenal have destroyed PSV in Philips Stadion, I don't think it's gonna be a hard match against Manchester United. Manchester United not even able to beat Real Sociedad. Arsenal lost several important players, but don't forget Manchester United almost lost half of their players.
They have a perfect match in Champions League round of 16 first leg, and with it they can have more freedom to think of a second leg and more important Premier League matches in coming weeks. Task for Arsenal in Premier League is winning and getting three points in coming matches, not because they need to achieve winnings and points to chase Liverpool, but their main purpose is to secure their second position. If they don't have too good performances and results, Manchester City can take over a second position in last matches of season.
Liverpool to not become a champion in this season is like 1% because they have many match against weak teams: Southampton, Everton, Fulham, Leicester City, Tottenham and Crystal Palace.
That risk is not too low like 1% but I agree that Liverpool have very good adavantage now and they have high chance to win Premier League title and with matches you mentioned, only Tottenham can get points from Liverpool.