Lexar has announced a 1TB SD card that will actually go on sale, although there's no official information as to when or for how much. The 1TB 633x SDXC UHS-I card is not a technical marvel, being only UHS-I instead of the faster II but still tops out at a read speed of 95 MB/s, which makes it a great choice for 4K and high-speed 1080p video or fast RAW capture. It was SanDisk that announced the first 1TB SD card way back in 2016 but that card will seemingly remain a prototype forever whereas Lexar say their card is going on sale. Source
Source: https://www.gsmarena.com/lexar_is_the_first_to_sell_a_1tb_sdxc_card_beats_pioneer_sandisk-news-35014.php
