To understand how musing would earn a profit you have to look at the bigger picture of the distant future.

For now, Musing has a delegation which it uses to upvote posts and earn Curation rewards. 

In future when SMTS are launched Musing could launch its own tokens or coins to gather more capital. They could even go ahead with receiving funds from various venture Capitalists who are always on the lookout for good,promising and disruptive projects.

But all of the above steps are simply capital formation its not revenue generation. For any project to earn Profit it has to generate revenue and generating revenue is an easy task when you have traffic on your site. Advertisers are always on the lookout to place their ads on the most visited sites. 

The token/coin could be used as prerequisite condition for an Advertisement to be displayed. That is, a certain amount of the token/coin would be mandatory for an advertising company to hold, to display its Advertisement, in addition to some fiat payment that would be needed. This would provide a use for the native tokens of musing and also generate revenue in fiat, which is necessary as well. 

But at the end, this is all approximation,speculation and imagination, nobody apart from the designer & owner of musing knows how he plans to generate revenue.