Lot of salty folks here. Nintendo clarified well in advance it wasn’t a Nintendo IP, as well as the treehouse livestream being specifically for Paper Mario.
This announcement was just an added perk, regardless if it interests you or not. All hype and anticipation was created by the fans, not Nintendo in the slightest. Plus with Wayforward having strong support for Nintendo systems it makes sense.
As for personal thoughts, game could be fun. I remember liking the series a while back and think they still show it on CITV in the wee early hours.
EDIT: As for the Castlevania wants, Konami is going out of their way to shut down all non-pachinko Castlevania games. They aren’t going to make a new one anytime soon.