as I got it some part of coins will go from miners to MinexBank. How large is that?
Blocks 1 - 900 001 = 20%
Blocks 900 001 - 1 800 000 = 30%
Blocks 1 800 001 - 2 700 000 = 40%
Blocks 2 700 001 - 3 600 000 = 50%
Blocks 3 600 001 - 4 500 000 = 60%
Blocks 4 500 001 - 5 400 000 = 70%
You can read more
https://minexcoin.com/html/download/wpeng.pdftnx, I got it and in accordance with this document it will be stable 20% starting from block 5 400 001.
Do you think miners will agree to pay 50 - 70% for the mining licence? But on the other hand such progressive payments will restrain the difficulty increase