The 4 largest public accounting firms care about blockchain for many reasons. Blockchain offers many opportunities for the big four. First of all it offers consulting opportunities. All of the uses of the blockchain are not yet known, so of course the big 4 would love to step in and help you think of many reasons where it can be used.
This is especially true in the financial services industry. It appears that blockchain has the potential to undermine some needs of using banks, so the big 4 will first pitch this hard to the banks. They will tell the banks that they need to invest in this and embrace it to avoid being obsolete.
Another area where blockchain seems to be valuable is in the transfer of securities. Maintaining records of security ownership is annoying and often painful. Blockchain would be extremely valuable in this area of financial services.
Make no mistake that the big 4 will be pushing most of their initial solutions to the financial services industry. This will happen for multiple reasons. One because the financial services industry faces the most disruption from blockchain and two, because the big 4 make the most fees from financial services.
There are also other industries that could be impacted by blockchain and the most common examples you see around the internet are vehicles, ownership, and health.
You see examples around the internet being used for vehicles. For example vehicle ownership. A blockchain could be set up to record all the changes in ownership for a vehicle.
A blockchain could also be utilized by a car rental company to make renting a car easier.
There has also been a lot written about blockchain being used in the health care industry. Data privacy in the healthcare industry makes it difficult to implement blockchain, but the healthcare industry is ripe for change. There are many transactions and many administrative costs with the healthcare. The efficiency of a central ledger that could reduce transaction costs has the potential to disrupt and improve the healthcare industry.
Additionally, all the tax implications of blockchain are not known yet. They will not be known for some time as all the applications of blockchain have not been determined. This means that big four will have ample opportunity in their tax services offerings. They will have opportunities in federal, state and international tax since this is a global currency/technology.