I remember not long after I upgraded to the Note 9 from the Note 8, the Note 8 received AR Emoji and other updates (I can't remember offhand) so yes there is a possibility the Note 9 could receive software updates rolled down from the Note 10.
The Note 9 has handwritten to text in Samsung Notes, not the same layout as the Note 10 and possibly not as many features (I don't know as I haven't played with a Note 10) but it's there already in a fashion.