The 2018 games are in Febuary and I haven't heard anything from that series. Those games aren't sales giants, but they do sell and being the sole party game on the Switch might have some value to it. 

Will we see one pop up?

When were the other ones announced? That would certainly help come up with a schedule. It could also just be that they decided not to make one for next year?

There have been games based on the Winter Olympics, though.

Does Sega still have the IOC-licence?

That'd be cool, but I don't see it happpening.

Probably going to be announced in a future Nintendo Direct, along with a release date. I personally could do without these games since we had lots of them already and they've always felt like "filler" games to me, but I know there's people who like them. I'd rather have a Wii Sports Resort sequel instead =P

They both like money, it's bound to happen.

Also, I agree with the guy who said Wii Sports Resort sequel/follow-up.

The past couple of games were announced months in advance, so unless M&S 2018 is being released next year instead of the usual Q4, I think the series might be on hiatus. Which is understandable, given how the sales for the series have constantly declined over the years.

The only question I'd have would be the future of Sega Sports R&D, seeing how they've only been working on this series for about a decade now.

Does Sega have any events over the Summer? Between this, Sonic Forces, Sonic Mania, that untitled SMT game, localizations of 3DS Atlus games, Total Warhammer 2, etc, they have a lot to potentially talk about.

The last game was announced only a few months before Rio Olympics, so the next must be a similar case. We will probably listen and see more about it between Dec/17 and Feb/18, or even later

It will probably happen, but no word of it at the moment