well, i guess that there also should be the question of who want to make castlevania?
to speak the truth i always have though that LOS series should have been a self contained trilogy, so i'm kinda glad on the news (and i did liked LOS)
what the series would need before LOS is probably some good self contained games (one or two) in the vein if COTM or LOD which aren't part of a larger serie, but pays homage to castlevania as a whole, and then keep experimenting with other things : )
to speak truth, after playing demon's souls and dark souls, from software would be amazing, and a challange for them too, since they have never done plataforming. just imagine dark souls with some good plataforming :0 ( and i'm pretty sure that dark souls have a little influence of castlevania, i mean, the final boss is a lord with grey beard and hair, with one of the most kick ass final bosses themes, who is also pals with a giant skeleton necromancer god kinda thingie, plus you are exploring a castle like city diverse areas, and you even have a clockless colcktower in Sen's Fortress) And also, this guys really know about excellent level design.
it could be a good chance to keep doing game while resting from the souls series a bit to gather great ideas from the next one :0
ark system studios could be another interesting pick so they can try something different than 2d fighters while still putting to great use their 2d visual styles.
and yes, ubisoft montreal studio could also make a quite interesting castle.
add one last igavania in the mix on some years more (so he can get more than enough time to get some ideas) as the 1999 battle thingie and you have possibilities for castlevanias for at least 10 years to come :0