The Futures price won’t drop on ex-dividend date, it’ll be adjusted. The adjustment is done such a way that the value of the position of the market participants, on the cum and ex-dates for the corporate action, shall continue to remain the same as far as possible.
So on ex-dividend date when the spot price drops, your Futures position will neither be in loss or profit. Also, check out this post for more information: Adjustment of Futures and Options contracts in ITC Limited