15-20 million in its first year, will give Mario Kart a run for it's money if the Switch at least 3 more years.

Wii Sports was very tailored to the Wii, a pack-in game for most of the world, and lightning in a bottle.

That said, Switch Sports is probably around 10 million minimum, with 13-18 million being likely. 20 million isn't a given, but not too outlandish.

I think it will sell 30-40m mostly based on legs. I don't expect it's launch to be terribly impressive. It will sell more like RFA. I think the launch of Switch Sports will be better than RFA, but not impressive at all compared to any other 30m+ seller.

I’d love it to sell exceedingly well: but the original game was explosively popular, it was all over the media for months and months. While there’s more than the usual amount of excitement for this game, it’s not the Avatar/Titanic/Marvel mainstream level popularity of the original. But I see some pros and cons.

Starting with cons:
1. Corona limits multiplayer. People don’t do gatherings nearly as much as they did in the Wii era, and I found the online multiplayer lacked the same sort of oomph that the local multiplayer of Wii Sports had. This is a bit of an obstacle.
2. The game feels like too much of a throwback. I feel like there’s something missing to take it to the next level, they still don’t have any kind of a calorie counter, or something that draws the progress of the whole experience together - that’s one thing I felt Wii Fit has over Sports.

On the plus side:

1. People wanna move. That’s why Ring Fit has been so popular.
2. Nostalgia. There’s something really great about returning to this world. The Wii and Wii Sports marked the beginning of a renaissance for Nintendo (along with DS Lite and NSMB which came out around the same time). This is a nice reminder of that time.
3. The price point is good, very easy to swallow.
4. The fact that we’re seeing an update schedule is promising, it means that Switch Sports is going to pop up in the media a few times which could draw in a lot of extra sales.

How much will it sell? I don’t know, I couldn’t put a number on it. There’s me, at least :D

I want to preface with I am fully aware that this game has the potential to reach huge numbers, but if I were to make a prediction, I'd say it probably won't. The install base on Switch is a lot different than what they had during the Wii days, even if it is technically bigger. I don't think a game like this has the same reach that Wii Sports did back in 2006-2010. Certain similar games of that era have proven to be successful, like Ring Fit Adventure for example, but in that case I feel it's a huge evolution to Wii Fit and still feels relevant today. It's the kind of experience that crowd would still be looking for and is catering to a modern audience as well. Switch Sports isn't as much an evolution as it is just the "next game" in the series, with likely some improved controls thanks to the Joy-Con. Wii Sports was revolutionary for being the game that introduced motion controls and even gaming in general to a massive audience, so 16 years later just being a similar kind of game, I don't see it hitting that kind of success, even with a decent marketing push and budget price, unless they decide to bundle it in with the Switch later on or something.

That said, I of course still think it will be successful, I just don't see it reaching even the top 10 list on Switch. It will easily hit 5-7m between nostalgia buys and those looking for a fun and casual sports party game like this.

20-30 million

Anything below 10mil would be a huge disappointment. 20mil is very much possible.

This is THE game that parents buy to play with their kids. So it is very hard to say. It is the "guitar hero" game from Nintendo. Corona has no impact at all. Nobody is avoiding anyone, especially kids. A Switch box with this as a pack in, but without the price increase? Could be a best seller this Christmas if priced well.

I’m thinking this is part of the strategy, a second wind so to speak, Nintendo is hoping for with the Switch.

So it entirely depends on promotions and marketing and how well the game is received - word of mouth.
Like if they have ads, for example, on daytime talk shows and soap operas and the like in USA and bundle it around the holidays then I’m thinking it’ll sell around 40 mil.