BCCI is hoping anything above 300 crore for the sponsorship and many companies have came forwarded with the proposal. The mostly likely of them would be the highest bidder among Baiju, Coca Cola India and Amazon. Even Patanjali is on the run for bid. The only question is how close would be the final bid to the VIVO's schedule sponsorship of 440 crores.
My conservative guess is that it is going to be somewhere around ₹100 crore, which would mean a decrease of 75% to 80%. Byju's recently entered in to a sponsorship deal with the BCCI for international matches, but I don't think that they have enough reserve funds remaining to go for another deal. Coke/Amazon may not be interested in such an expensive deal, because they don't need it. Patanjali maybe interested, but for them the potential returns from any such deal may not be that great.