IGA's timeline still stands as the official canon for the series. There's a good chance Konami will return to it.
The 1999 game is a must; otherwise, there are still a few spots here and there that can be filled for a new game, if it comes to that.
Of course, we're bound to reach a point where the original timeline will have become overcharged; Castlevania will eventually need to move on to something new. For that purpose, I'll echo Chernabogue's thoughts:
Let LoS2 end the LoS timeline.
Let someone make a 1999 game to end IGA's timeline for good.
Make something new and good.
No LOS in the poll? this timeline is still virgin and has the potential to be explode for good in the right hands.
No. Lords of Shadow leaves with MercurySteam. That's how it was intended to end, and that's how it will end.
Seeing a sequel or a prequel to CotM would be very intriguing, but sadly not something I see happening. Perhaps if Ko-G would direct another game in the series again?
How I'd love to see that. But I don't quite see it happening, either.