Yes there is a HATAKE clan. Only thing is the members have not been shown on the screen yet.
Same goes with Minato, Namikaze clan exists too.
Because until recently I did not think there were any more members of the Sarutobi clan only for them to line up in the war.
I don't understand why that means the Hatake and Namikaze names are clans. There has been very little evidence thus far to suggest they are clans.
Sarutobi clan is completely different. Firstly, Kishi already specifically stated they are a clan back in chapter 533.
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As you can see, their clan has always had a very special relationship with the Nara, Yamanaka, and Akimichi clans.
But in the case with Hatake and Namikaze, there has been nothing in the manga to suggest that they are clans. Now, I'm not ruling out that the fact that they are clans - they could still be clans - but thus far, manga hasn't said so.