I'm surprised I haven't seen this posted here yet. On April 5, 2024, Fujifilm posted this (in Japanese) notice to their website, announcing the discontinuation of Fujifilm Fujicolor Superia X-Tra 400 and the introduction of "overseas" Fujifilm 400 to the Japanese market. Nothing is said about Superia Premium 400, or Fujicolor 100. Slide films are not mentioned. As much as I hate to say it, I'm sure Provia and Velvia will be gone soon too. Superia 400, being a cheap color negative film found everywhere, probably outsold Velvia and Provia combined by a decent bit. If Superia is dead, then Velvia and Provia are probably only around until stock is gone. I pasted in a screenshot of the translated webpage below.