banks are already involved.
but although elwars OP mentioned leveraging (fractional reserve) upto 10 times, as being the issue. its not.. elwar forgets one fundamental flaw
for every trade there is a buyer and a seller
say you buy bitcoin using fiat.. that fiat is not burnt and taken out of circulation.
instead its handed to the person that had bitcoin and wants fiat.
thus the amount of fiat does not decrease. the only thing that changes is who the account holder is of said fiat.
EG
Bank has $1bill total(dumb example), spread over accounts for persons A,B,C,D,E (all having $200m each) and accounts for persons F,G,H,I,J have $0
A-E want to buy bitcoin. F-J want to sell bitcoin.. funds move between account holders.. but the bank still ends up with/has $1bill total and nothing has changed for the bank.
yes a bank branch in Mississippi may end up with less total than bank branch in NYC. but from the HQ point of view its still $1bill.
meaning that HQ can still then 'create' $10bill in 'credit'(mortgages), which yes the HQ can refuse to let the Mississippi process mortgages due to internal metrics, and allow NYC bank to increase mortgages but from the point of view from the top. its still has the same total of mortgage creations.
i say this because banks find it hard to get beyond the $1bill(dumb example) cap of real(zero-debt) balance. because fiat is just a cauldron being stirred of the same money going in circles.
but by offering exchange services where they take a 1% cut. can make that $1bill cap grow, which in turn makes their fractional reserve allowance grow.
the issue is not the fear of bitcoin destroying fiat.
the issue is the local bank branches having laws to only play with fiat.
this is why people cannot play the stock market from a bank branch teller desk or an ATM. but...
the HQ has subsidiaries who can play with exchanges to make their small % often. and customers can apply to these subsidiaries to 'invest'/exchange.
and now my point.
bank customers will not be able to walk upto a conventional ATM or enter a conventional bank branch and swap fiat for bitcoin due to many laws concerning legal tender. (not the worry of Fractional Reserve)
but those banks subsidiaries will have 'services' to allow swaps, just like bank customers CAN'T trade shares on an ATM or bank branch but can contact the subsidiary to trade shares via the brokerage subsidiary.
if you dont believe me that banks are already involved. check out hyper ledger.
R3, (banking group linked to classic) DigitalAssetHoldings(banking group linked to blockstream/core) creating their new international fund network with all the side chains, etc.
proof:
hyperledger ties R3 and DAH -
http://www.coindesk.com/hyperledger-technical-steering-committee/DAH for instance building the blockchain for bank of england, bank of india and deutsche bank.(google RTGS blockchain digital asset holdings)
the only issue is that bitcoin will not be the international monetary fund (reserve currency) where all 'hyper ledgers' circle around bitcoin. instead bitcoin will just be a small side 'asset' that banks subsidiaries(hyperledger) would allow swaps with to take a middleman % cut