Some of the sources linked below might be helpful to you! While none of them explicitly ask and answer the question "is mass marketing alive or dead," they all discuss contemporary marketing and the relationship between mass marketing and other types of marketing in the context of our society post-2010.
Reading over these, the most common conclusion seems to be that, while mass marketing may not be dead, the internet has led to it fading in popularity as targeted and relationship-based marketing have become more prominent. With the internet, businesses can pinpoint their most likely customer bases instead of trying to sell to everyone. Additionally, social media means many businesses, even big-box chains, use platforms like Twitter and Facebook to build relationships with their customers.
There are many businesses still using mass marketing, but this is now considered "traditional" marketing. Most successful businesses, if they do use mass marketing, are combining it with these more targeted and individualized forms of marketing by cultivating their web presence.