Not sure what the video says, but the S9 will probably be announced in February... and unless the phone gods are crazy it will most definitely not launch in August if that's the case. The Note line is fine, and will still exist.
I think it will exist too of course! It does make me wonder if the plus Galaxy and Note would be merged since the S8 Plus and Note 8 are very similar for example minus the spen and 6gb ram. Why have a S9 Plus and then the Note which both have nearly the same size screens?
Again, that's just my thinking. Plus production cost too of having only two flagship models instead of 3. I still own the S8 Plus and besides the spen, and the Note being a bit more snappy, it's not much different than the S8 Plus.
If I were samsung I'd' have the s9, same size as the S8 screen, and then the Note 9 instead of S9 Plus and rename it the Galaxy S9 Note. That would cut down design and production cost.
Unless Samsung likes having the separate Note line that releases at the later time because of people like us who will buy the s8 plus and then turn around and pay full price again for the Note 8 LOL.