Well, smart contracts have been proven to provide many use cases for the mainstream world. Whenever they become fully adopted by our society is yet to be seen. So far, only a small number of startups and companies have made use of smart contracts to provide different services to their customers. However, the limitation of scalability within popular smart contract platforms (not limited only to Ethereum) has made many entities wary of adopting the technology for their own benefit.
Despite this, smart contracts main uses have been the launch of ICO tokens. But, the recent crackdown from governments (especially the US) have slowed the growth of such tokens. Perhaps, in a couple of years from now, smart contracts would become more useful as their underlying blockchain networks improve every step of the way. Only then, the mainstream world would adopt them at a large scale. Just my opinion