Interesting article. I agree with the author that all the current "series" of the franchise have pretty much been run their course. Now the most interesting thing would be for the series to branch out and try different things. The author apperently thinks that's a negative thing, but I wouldn't see the harm.
Regarding Castlevania in the future, I made a topic about that a little while ago. I think it would be fine as long as they could retain the "creepy castle in the woods" setting. Then they could introduce plenty of modern technology. But yeah, if it would just be jetpacks and laser whips then it would indeed be terrible. That's why LoS2's modern city is so awful in context.