I believe it fell down after the Alucard 360 game was cancelled, 1999 wouldn't have come out on any of the systems at the time, or it would have been a 3D game
IGA would probably had made 2 or 3 more games some random place on the timeline before 1999
IGA's two major "gaps" in the timeline that were events and not games were the Quincy Morris story and the Demon Castle War, so those were probably what he was narrowing down towards.
I may also be wrong with the dates here, but I believe in 2007 PORTRAITofRUIN (remember that leaker, fam?) mentioned there were two 1999 games in production, one for the DS and one for the PS2. Julius was to star in one, and Alucard in the other. I believe these projects both got cancelled as the only game released in 2007 was Dracula X Chronicles, a largely outsourced game. I believe the 2008 Alucard game was just Konami Japan's pitch for the series, which was largely struck down because of MercurySteam's pitch and the influence of Hideo Kojima.
Thats the only way i can see a new 1999 Castlevania happening, Bloodstained is a huge, huge success and suddendly Konami is interested in giving the license to Igarashi, that and the continuing popularity of the Netflix series and Smash.
Who knows, stranger things have happened on this industry
It seems the series currently has an unnamed producer, one that Konami is actually trying to hide very well. He/she is not credited in either the Netflix show or the Anniversary Collection by name, even though this person has overseen both projects, and is probably producing Grimoire of Souls, the post-Dawn of Sorrow mobile game. I know IGA approved of the
draft to the Netflix show, but that was all the way back in 2007 or 2008, so I don't think he's somehow secretly the guy pushing the series again. It would be some crazy work to have him secretly be pushing 'vania as he's literally making Not-'vania. :p
We also have users on this very forum mentioning how Konami wants to "counter" Bloodstained, so I take this to mean they actually are planning a video game that isn't a collection. Dusk Golem was one such user. In fact, Dusk Golem's post
is very interesting (though this isn't the post that mentions they wish to "counter" Bloodstained, which I believe was a more direct post about Castlevania and Bloodstained) as the only thing that's not checked off from that post
is the Konami bit.