These exchanges arent going to build there own block chain. They think that the technical limitations are that of bitcoin. Nasdaq has no clue that it can use a block chain for trade execution on the scale that they're accustomed. They are only looking at it for post trade services.
Also have you missed the memo on the compliance features that have been implemented in graphene. Exchange can remain fully compliant if they so choose. Nasdaq is also a huge proponent of open source and I don't think thats a deterrent. They wouldn't use this for their equities markets. Where this is most needed is in the standardization of OTC products that aren't currently exchange traded.
why don't you think exchanges won't build their own blockchains? i'd say it's a strong possibility. either that, or subsets of financial institutions forming collaborative, but still privately operated, chains. i'd also strongly assume that what we're doing here with Bitshares is fully on the Wall ST radar; these guys aren't idiots, money can buy a lot of brilliant minds.
good point re: the OTC assets...i can see that being a first step to apply the new tech.
First of all, it's impossible for a centralized entity to create its OWN blockchain. That is contradictory. They would just end up with a database. Maybe a distributed database, but not a fully decentralized database, a.k.a blockchain. Perhaps they could create a ledger distributed among multiple exchanges, banks, and/or financial institutions in which all entities compete among each other to validate transactions and change parameters on the network, but it's difficult to tell how decentralized such a system would be. Likely it would be even more centralized than ripple. It almost surely would not be opt-in... we could call it a psuedo-blockchain, but not a real blockchain such as bitshares or bitcoin. The best chains will be the ones that started from a grassroots effort and grew organically over time. Chains started and maintained by the establishment will most likely not keep end user interests in mind with regards to monetary inflation, theft, confiscation, ect. In other words, they will be more centralized and consequently less secure. Their best bet is to adapt to the technology already being produced, and many of them are doing just that.
My grand vision would be for exchanges such as the nasdaq to replace their backend databases with the bitshares blockchain, doing so in a way that users retain control of their assets at all times, even when in trade or under contract. I imagine we are quite a ways off from this becoming a reality.