Super Mario Bros. 35 was discontinued on April 1, 2024. According to the president of Nintendo of America, Doug Bowser, the 35th-anniversary products were discontinued due to the 35th anniversary being a celebration that was intended to be unique.
Super Mario 64 is no exception, with it being the defining game of the N64 console. It's the rarest Not For Resale Mario game, but there are even more rare variants.