I'm expecting one of two things to happen, but am not sure which of the two will happen.
1. There will be one or more Lords of Shadow sequels/spin-offs.  Then they'll pick up where they left off with the original timeline and work with it going forwards, occasionally producing a gaiden here or there that's loosely connected to the main timeline (like Order of Shadows), but not necessarily acknowledged by that timeline.
2. One or two Lords of Shadow games will be created.  Then Castlevania will be passed to a new development team unrelated to Iga or Mercury Steam, which will then create its own "reboot".  This could continue so that there are three or more timelines that aren't really connected to each other.  The original timeline might then be only occasionally revisited.
I will be saddened if #2 is the outcome though.  Over the years, it has been great how all these different games created by different folks all connect to each other in some fashion.  It would be a shame if new teams feel the need to start from scratch all the time.
Edit:  I think the Neo-Retro scenario posted by LordsOfShadows is also a possibility.  Kind of reminds me of the Transformers cartoon franchise, where you start with a long series of connected shows (Seasons 1, 2, movie, 3, Japanese seasons, Beast Wars/Beast Machines tangentially), then end up re-creating the franchise several times over with separate timelines (Unicron Trilogy, Transformers Animated, live action movies, others), and then eventually create a new "modern" timeline that combines fan favorite elements from all the past unconnected franchises and moves forward with it (Transformers Prime).