I want to calibrate the number of notary nodes based on 10 year coverage from ICO funds. As KMD price grows, the need for subsidy is reduced, at $1.25 per KMD price, all 64 notary nodes are fully paid for just from the mined KMD.
So anything over 5000 BTC raised (assuming BTC price stable) would provide this coverage, though it needs to be adjusted by the BTC transaction fees upward and by the value of KMD downward.
So I will just set the number of official notary nodes assuming 10 years of 100% subsidy. That will almost certainly be on the conservative side.
Now in about 14years or so, the block rewards will stop due to reaching maximum coin supply from the 5% APR interest. So the daily txfees will be needed to pay for the notary nodes + btc fees at that point.
Since KMD has 20x the tx capacity as BTC, assuming dPoW is adopted by other blockchains, then there should be plenty of txfees