During the 1980s and 1990s, there was a plethora of excellent track and field games that became incredibly popular, such as Summer Games, Track & Field, Athlete Kings, Virtua Athlete, and many more. There has been much debate about the reason for this (many believe that the pursuit of more realism and less of a "mini-game" feel contributed to the decline), but today the genre is largely extinct.
There is, however, one exception that still sells well and gets a lot of attention: the Mario & Sonic series. Unfortunately, even that series seems to have taken a hit, and the latest game was released in 2019, namely the Switch title Mario & Sonic at the Olympic Games Tokyo 2020. We reviewed it and gave it a high score, but if you want to buy it, you should act fast.
Nintendo Everything notes that the game has now completely disappeared from the eShop in several major markets - including Australia, Japan, and the US - although at the time of writing, it is still available in Europe. This means there's a pretty big risk that it won't be available for purchase much longer (though if you already own it, you can still download it again). That means anyone who doesn't own the game but still wants to enjoy Mario and Sonic's slightly more colourful Olympic Games in the future will have to get a physical copy.
We highly doubt that more cartridges will be manufactured either, so if you want it, you'll have to seize the opportunity. A quick check with major retailers shows that it's still readily available... at least for now.