Yes, it's a good start for Lewandowski. And Lewandowski needs to know that this is nothing as La Liga is just into its fourth week. The real competition will be seen at least as the season enters the middle towards the end, because even one goal will be very important to affect the position in the top score table.
There is no doubt that Lewandowski is playing well. At the same time they aim to perform well in La Liga and the Champions League. If Lewandowski can maintain his fitness and stay in form, it will be easier for Barcelona to perform consistently well. I think Lewandowski will definitely want to win the Ballon d'Or this season. And for that, apart from scoring more goals, Barcelona also needs to win the title.
For a chance like you said maybe it can still be done but still these are only a few possibilities because considering this it is clear when in La Liga there will be Madrid who are ready to tackle them, not to mention for the Champions they will still face a difficult group.
Lewandowski Balon d'Or? Still can but obviously there are some people who still have more quality and the biggest chance now is Benzema of course.