I think that Nu network has to find a diverse income to eliminate the need to the fractional reserve, your suggestions about the short term lending and the price spread are great examples and i wish to see this community discussing and experimenting more new ideas.
I see Nubits as a great service, so i suggest to substitute the destroyed 0.01NBT fee per transaction, by a various relative fees according to the transaction volume, i.e :
0% <= 1NBT
0.05% <= 1000NBT
0.1% > 1000NBT
If we notice the Daily trading volume and compare it to the total Nubits sold until the moment, i can argue that the revenue can be significant.
If Nubit succeeded being a stable and sustainable currency, the trading volume will be doubled by many folds, so why to sell the currency once and compromise the system with the fractional reserve, if we can have a share from every transaction in the new economy that Nubits facilitate? Especially that Nushares holders are minting all these transactions !