I liked DoS' use of the Stylus. And I would love to see the alternate story's ending be the cannon. But either way, it does not end the Castlevania story. It just stops Dracula for a generation, more or less. I could easily see a future Castlvania where Soma fully embraces his destiny.
Now PoR makes me wanna see Castlevania 1999. That one will be the biggy.
Also, they are gonna run out of reincarnations pre 1999 soon. Since Dracula's begining has been established as the 1300s, and the games leave little place to add more story, I really think the next big Castlevania will be the assault of 1999. And at that point, it will be interesting because it was Justin Belmont, a bunch of soldiers, Yoko Belnaldes and Alucard, all at once, in the castle fighting Dracula. And the only 4 to survive were Hammer, Alucard, Yoko, and Justin, if I remember correctly.