Not too big of a surprise that this mode is coming back. Introducing a boss battle is a good idea, since the devs have done great boss battles in the single player.

This is my fave mode out of Splatoon 2 so it's nice to see they'll be expanding on it.

Same. This was one of the things that kept pulling me back when I wasn't really feeling the ranked modes.

I do wonder what new modes they'll introduce, but I guess they're saving that for a Spring Direct.

My guess is they only introduce one new mode. That along with a new single player campaign and new stuff in the other modes. You can only break up the player base so much, hence the time slots for Salmon Run.