1) Bond issuers have backends that they have to manage. Billions in legacy software and assets. By being able to unify the ledgers then that will reduce the need for them. So anyone involved in the backend will be affected, programmers, administrators, managers, clerks. They may not be gone but their numbers will be reduced.

2) Cost of financial instruments will be greatly reduced so companies will be more likely to do the work in house. The number of financial firms will be less therefore there will be less jobs in what is now the financial industry. New jobs expertise will be needed but current expertise are at risk. Middle men will be reduced. There will be a Google/Amazon type of player that will eat the industry world wide.

3)The cost of issuing debt will collapse so anyone involved in loans will be affected.

There are many other ways that Blockchain will impact the industry but these are the ones I can think of right now.

How long? Who knows. But it will be here faster than expected. For timeline, here's one to ponder. How has the cloud affected network admins in the last 10 years? The impact has been large yet it's only been a few years since it first started.

The "jobs" this technology replaces were computerized in the 1960s and 1970s. The application of the blockchain only speeds up settlement because there is a single ledger between multiple parties.