Is that a guess or do you know something more?
What I know :
1) The decision that LOS is the last LOS (for MS) took nearly two years ago.
2) Shortly after, Konami began to think about the future (at that time LOS had no as important as now for Konami)
3) Last trips to Japan from MS and Cox ( recently) was to discuss the new project and to discuss the launch of LOS2 . At this point I have to say that change their policy , they went on to say that the PC version is the "next -gen" , did not expect sales of such large consoles XBONE and PS4 , (almost 7 million and this Christmas many more . . ) have concern about whether these sales may affect sales of the game . Why let a little more freedom to the PC version ( these months improved a little ) and they say it's the most graphically spectacular . ( Although the PS3 version I've seen looks very good .. ) . Try guide or encourage as PC sales to fear about possible few customers Xbox360 and PS3.
4) Contrary to what is being rumored on NeoGAF by Cox misinterpreted statements about the PC version , they will not make a version for next-gen , the reasons are clear .. does not make sense to take out a next-gen game that came out a year ago for other platforms with just a few graphic improvements (60fps , full HD) , the authentic fans will already have purchased in other formats. If it were to attract new fans because it would not make sense that would have a game without LOS1 and MoF.
Did this discarded? no, but not for MS, maybe Konami do, but not something that is on the table, especially since both Xbone and PS4 may play LOS2 "virtually". Sales would be small and the great effort, it is something that is very clear and MS Cox. But what Konami do in one or two years .. only they know (anyone said FFX HD?
5) Returning to the original question, Konami began searching options for the future, the resurgence of the Castlevania name gave opportunities to retake other projects, there is a project out there for portable platforms, Konami are very big heads lately with LOS but ... no study has begun to LOS3 .. Enriz Alvarez give them the LORE before Gabriel. But there is 0 LOS3 fact (have not even started yet ... the LOS2 DLC). Two years it would take to get a set of quality of LOS if they start now. Unless Konami milking LOS doing a shit for "Live" and "Plus" (which can be done in 8 months). So Konami bet on what they had initially thought, does an old game canon? I do not know. But right now is more likely to succeed where they have, also not risk much Konami (Kojima is no longer there to risk instead). If this new game succeeds is possible to suggest Konami that there is life farther than LOS in Castlevania.
My personal bet, if there will be a different castlevania soon, but Konami will also squeeze LOS at least one more game.