Last year, they did a direct for Arms about a month for E3, and they probably did that cause they knew that game was coming out right after E3, so they didn't wanna waste any time discussing it at their E3 presentation.
I think there's a good chance we could have a direct for Mario Tennis by the end of the month, only factor that makes me somewhat doubtful is that Arms was a brand new IP that some people might've been skeptical about (the way they presented at the Switch presentation earlier that year made it come off as a gimmick game, when it was far from that), while Mario Tennis is a series that people are significantly more familiar with.
Then again, Ultra Smash was a thing...
"Just for comparison Uncharted 4 was 20x bigger than Splatoon 2. This shows the huge difference between Sony's first-party games and Nintendo's first-party games."
