With they hyper saturation of Velvia.
On the more realistic side they had what I think was possibly the best slide film ever in Astia. But the loud crowd (Velvia) won over the realistic crowd.
I think the reason velvia "won" was because of the times, how and what people are shooting. in the last 10 years or so, the average person who was mainly shooting quick snap shots, or more likely, people shots, went to digital. I would assume had they not went to digital or it was never an aoption, they would be using the lower contrast lower saturation films everyone has mentioned. that left more of the landscape shooters, who have preferred (not always) the more velvia like films. most of the serious landscape/ thing shooters stuck with film or use it alongside digital. so those type of films outsold over the last few years, the more people type films. I would assume if you looked a film sales spreadsheet for say kodak over the last 10 or so years, you would see a trend showing that. hence the reason they left slides all together. same for fuji. they continued to show strong sales of velvia styles and less so with astia and 400x. hence the reason they let them go alongside their neg films.
Also, more people when they did shoot film, shot c41 for people sales. hence kodak dropped all reversal films and focused on neg films wioth Portra being their main film and trying to keep the saturation people happy with Ektar. fuji dropped their neg films except one and their mellower slide films and kept the saturation over the top films. unfortunatly its marketing 101. keep making whats selling and drop whats not.
if sales of provia 100 went up substantially maybe fuji would take notice and bring back 400x. i see no reason they would bring back astia though. and forget kodak. its now being run as a business as a stand alone. at least fuji is a much larger more diversified company and could continue to carry less volume films in their catalog. At least they still make new med format cameras.