I imagine Hero's gonna be releasing in July, and Banjo in early October. His exact release date and DLC4 will be announced in the September Direct. DLC4 will release in early December, and DLC5 (and possibly DLC4's release date) will be announced at TGA 2019, with a release of February 2020 for DLC5.
That way, they'll have a character every 2-3 months from here on out, till Feb 2020.
Means absolutely nothing, though. Even if they've talked about Smash, for all we know, Bethesda brought it up and Nintendo was like Nah, and it'd still be correct to say they talked about Smash.