Except any reasonably complex interactions between parties which may or may not be accounting applications yet still need a distributed system of trust.
Registered assets are always more secure and cheaper than bearer assets. And if you needed bearer assets, there's multisig, which does everything turing complete code does, cheaper and more secure
I don't talk to their developer teams so I wouldn't know. I wouldn't expect them to move quickly enough for that to have been publicly announced by now. My guess is either ethereum or hyperledger fabric depending on how much of their system they would want completely public. Queries per second is a huge concern there too, so it might be a while off for NYSE for this reason alone.
Which includes a few trillion dollar industries.