I noticed that the buy-back Value (VIP-4) for burning did not decrease the cap of VALUE. It means adminkey holder can mint those burnt token again.
Since we will cut off the connection between YFV and value, we can simply adjust the cap.
We should set up a new cap as follows：
new cap = old cap - unmigrated YFV amount - burnt amount - adjustment constant
adjustment constant is used to ensure that the total supply is integer (which may be benefit to marketing)