Did you read the article?
This doesn’t just cover microtransactions. In fact, the new law is harsher on fake gambling than it is on real gambling - loot boxes get classified as M, but a poker minigame is an automatic R18.
Apologies for editing after you replied, I have a tendency of making a quick point and then expanding on it with an edit.
Hard to copy and paste lots of shit on a shitty phone.
But basically, its not a retroactive re rating of any game unless the game is patched to add in simulated gambling or loot boxes.
While sure, Mario Party 3 has simulated gambling minigames, I doubt its getting patched any time soon, and the upcoming Super Mario Party Jamboree does not appear to have any mini games simulating a casino type game.
EDIT: sorry for another edit lol, but yes, I do think its stupid that a poker minigame with in game currency only, which cannot be purchased or redeemed for real currency, is rated worse than a game with lootboxes.
But basically, its not a retroactive re rating of any game unless the game is patched to add in simulated gambling or loot boxes.
This FAQ say titles will need reclassification if the modify their loot box payouts, so any ongoing live service game will get an updated classification eventually.
Q. Would changing the rewards within an existing paid loot box, cause the video game to require reclassification?
A. Adding new rewards to existing paid loot boxes constitutes adding new in-game purchases linked to elements of chance and may cause a video game to become unclassified and require reclassification depending on the original classification of the video game.