Just a reminder that Yoshifumi Hashimoto started his own development team (HAKAMA -
http://www.hkm.co.jp/ ) under the aegis of Marvelous last year. They've previously worked on Dragon Marked for Death and are the team handling both Rune Factory 4S and Rune Factory 5, and it is probably safe to assume that HAKAMA is primarily staffed with Hashimoto's old team from Neverland.
As for Story of Seasons proper, a new mainline title was announced during the February 2017 Switch prelaunch event, but we've heard almost nothing since then. Since then there have been news articles stating that the next game is being developed
or that they are considering developing the next game. I don't want to speculate too much, but maybe Hashimoto's team branching off led to some kind of scrapping or full revamping of the next BokujÅ Monogatari/Story of Seasons title? That would account for both types of news being released in the last two years. Again, this is just my speculation based on publicly known developments and news articles, I have no insider knowledge. Or perhaps it is just a translation mishap as suggested above and the new game is right on schedule. I imagine developing a HD(ish?) title for Switch would take a lot more effort and time than pumping out a new DS/3DS game every two years, especially since they haven't made a dedicated home console BokujÅ Monogatari/Story of Seasons title since Animal Parade in 2008.
As Bandai Namco and Brownies are the ones making Doraemon Story of Seasons, I very much doubt that game has led to any significant delays of a proper mainline Story of Seasons title.