The use of blockchain approaches is more and more discussed, however, often from a technology point of view. What is the business impact? How it it used in practice - besides the bitcoin application?
I think at this point people are exploring the non BitCoin uses of BlockChain technology, so it seems premature to talk about definitive business impact so far. There has been some simulated bond trading done using BlockChain done by the R3 bank consortium (link below) I suggest following the hyperledger project (link below) along with a project to handle derivatives with blockchain (link below). I find the last one interesting as one of the project managers says it is worth the effort just on cost savings.
As for the first part of your question, in my opinion, blockchain technology is applicable whenever secure transactions are needed, e. g. e-commerce payments, electronic voting systems, IoT transactions.