Nope that's never going to happen, Gmail is the cornerstone of G Suite. As of January 2017, G Suite has 4 million paying businesses, and 70 million G Suite for Education users.
I see no reason to cancel it or not, but those numbers seem pretty small relative to google's general user base and revenue.
I have no idea if or why they would cancel it or not, just saying that the numbers you gave seem like small potatoes. Then again Google really needs to show alternatives to advertising revenue (e.g. why Nest was brought onto Google's balance sheet).