They're been talking about its profitability at investor days and interviews for 3 years, and expanded from an 11 aircraft to 34 equipped that way. All signs suggest it's been the main driver of profitability these last few years at Jetblue:

https://www.fool.com/investing/2016/...es-growth.aspx
"This week, JetBlue provided the most detail it has ever offered to quantify the financial impact of Mint. Before Mint's introduction, JetBlue's New York-Los Angeles route was significantly less profitable than the system average -- and the New York-San Francisco route was even worse.

However, in the course of two years, the LA route's profit margin improved by 17 percentage points relative to the system average. The San Francisco route's profit margin improved by 18 percentage points. This has made them two of JetBlue's most profitable routes."

https://seekingalpha.com/article/416...nscript?page=3
"Our most mature Mint routes again saw RASM outperformance system in the first quarter."
"But I will say that Mint's been wildly above our expectation."

Seems like -- from their on-the-record public statements -- that Mint is making bank for them. I wonder if AA's domestic first product could do the same?