To be fair, Sakurai said they had no plans on an FP3, not that there wouldn't be, and he said this before FP2 characters started releasing iirc. So, they could make more plans during FP2, just as they did for FP2 during FP1.
Of course, there's nothing suggesting they'll actually have an FP3, so it's not a sure-thing either. Nintendo may be happy with all the money coming from the DLC, but that doesn't mean they'll push Sakurai further on; they may be satisfied with what they've achieved and end the DLC there.
Personally, while I'd like an FP3 and more characters, I wouldn't mind this being the end of the road; all the bickering and speculation and stuff is tiring, I really should've taken a break from it all tbh. The hype cycle isn't all that nice, it's just fun getting hyped/happy over stuff you like and seeing others happy too, but with it also comes the negative stuff; not the cool and reasonably disappointed people, of course, disappointment is always fine and being skeptical about some things can be good. I also let my stubborn side get involved in silly arguing, even if I still tried to stay respectful and never used rude words although I was heated sometimes, so that didn't help...