Vijay ;

You can't say much about the cutoff without knowing how many students have applied for it.  Now just the application for paper1 has started. So, we can't say much how many more will apply for the paper 2. But looking at all possible scenarios, I don't think there'll be much decrease in the cutoff percentile. The marks though will surely decrease, as starting from this year the JEE main exam is going to be conducted of 300 marks. So, considering that and the toughness of the paper the cutoff marks might decrease. But, in the percentile sense there will not be enough variation here.

Hope you get your answer!