Nintendo owns a few long-standing franchises in the videogame industry, and as such, it often celebrates the history of those franchises for their more notable anniversaries. Mario has seen a few such celebrations - in 2010, the company celebrated the plumber's 25th anniversary with Super Mario All-Stars - 25th Anniversary Edition, and in 2015, the 30th anniversary saw the release of the 8-bit Mario amiibo, as well as the first Super Mario Maker.
According to a report by VGC, corroborated by sources at Eurogamer, Nintendo could kick things up a notch this year. The company is reportedly planning to re-release "most" of Mario's catalog of games from the past 35 years, remastered for the Nintendo Switch. The reports don't specify exactly which games would be included, but Super Mario Galaxy, a 2007 Wii title, is reportedly in the cards, alongside other 3D Mario games. There's some room for speculation, but there aren't that many 3D games in the main Mario series, so other possibilities would be Super Mario 64, Super Mario Sunshine, Super Mario Galaxy 2, Super Mario 3D Land and Super Mario 3D World. Super Mario Odyssey is already a Switch game, so it wouldn't make a lot of sense for Nintendo to include it.
It's unclear if these games will come in a single collection, but Super Mario 3D World is said to be getting a standalone release as a Deluxe version, similar to what happened with New Super Mario Bros. U. It's no secret that the Wii U didn't sell nearly as Nintendo would have wanted, and there have already been a few titles re-released on the Switch, so this seems like a logical move for Nintendo. The company is reportedly planning even more Mario titles for this year, including a new Paper Mario RPG.
The rumor provides no indication as to which 2D Mario games could be re-released, but it's worth noting that many of them are already available on the Switch through the Nintendo Switch Online subscription. Whether or not that will stop the company from including them in a new collection remains to be seen.
Of course, when contacted, Nintendo refused to comment on the report, so we'll have to wait and see. The announcement of these releases was reportedly planned for this year's E3, but the event has since been canceled, and the coronavirus pandemic that's been affecting the world could affect that schedule.
Update: Additional reporting from Gematsu has confirmed that Super Mario 64 and Super Mario Sunshine are also set to be included in this set of re-releases.