Depay must end his time with Barcelona, he will find it difficult to break into the main squad after Lewandowski arrives. Moving is the only way to save his career, Tottenham are very interested in signing Depay, he can move to Spurs for guaranteed playing minutes. Depay's departure will also leave the number 9, so Lewandowski can inherit the number 9 left by Depay.
At the moment Spurs are stacked with midfielders and need to let go of a few. They don't have enough creative midfielder though but I don't really think Depay fills into that role. He's definitely not starting for Spurs when they have likes of Son, Richarlison, Kulusevski, Lucas Moura and loads of midfielders. According to recent news, Borussia Dortmund are interested in him.