Barcelona can afford to play even without Lewandowski and I also think that Memphis Depay is a great striker,he showed that with Netherlands in the World Cup we just left behind.Real Madrid has got nothing to do with this,they need to win their games but they can't rely on the fact that without Lewandowski Barcelona will have difficulties winning games,the strong point of Barcelona is their midfield as it is exactly the midfield which wins you or loses you the matches.
Barcelona has the capacity of winning even without Lewandowski but of course the fact that he will not be playing may have some sort of impact in the team but not up to the level that they should not win games.
However, however, we don't know for sure whether Depay will be able to give his best during the match vs Espanyol, Ateltico Madrid and Real Betis. this is a challenge for Xavi, as well as the cohesiveness of the Barcelona players later. I don't doubt Depay, he can be counted on when Lewandowski is absent. even so, Lewandowski's absence will greatly affect Barcelona's sharpness later. fortunately in the match vs Espanyol, Barcelona played at home, Camp Nou. but for the next two matches, Barcelona will play as a guest team. and I think without Lewandowski Barcelona will lose a bit of sharpness. but, we cannot predict in detail. the reason is, maybe Xavi has prepared other plans and strategies to face Espanyol, Atletico and Betis later.
As for El Real, they have no problems when playing the game later after La Liga is rolled back. Real Valladolid is not a tough team for them to overthrow, maybe only Villarreal will provide a little resistance. so, Madrid has the potential to shift the ranking at the top of the standings if Barcelona slips in the match later.