They didn't kill the Note... but just with direction of phones its become less relevent...
S4... S5... S6... S6 Edge... S7... S7 Edge... a phone that had a 5", 5", 5", 5.1", 5.1", 5.5" screen.
At the same time you have the Note 3, 4, 5, 7 that had 5.5", 5.5", 5.5" 5.7" displays.
I mentioned before, the Note series is more of a niche phone... S-Pen and from beginning bigger screen over most regular phone... a phablet. And I think the Note got the higher specs over that years Galaxys. They usually used the Note to showcase the latest specs.
This year the difference between the S8+ and Note 8 will be pretty much .2" in screen size with a pen and updated camera that they couldn't get into the S8 in time. Where there is some pen features you'll never get on the +, there are some they gave like gif creator. So where people went with the note for the pen, but I suspect more for the larger screen and usually higher specs, there is a lot less reason to. S9 and Note 9 I imagine the gap will be narrrowed even more.
I would hate to see phones get bigger than the S8+ and the Note 8's 6.3 in future phones so not sure what direction Samsung needs to take the Note series. I've always hated the iPhone + size and am pretty excited the rumored iPhone 8 models have been in between. Perfect size IMO.
I see Apple eventually, if not with the iPhone 8, add Apple Pencil support to their phone. If they do that then Samsung will probably follow suit with the +. If Apple does it, it will be a $100 accessory for the pen. Samsung can do the same. If they keep with 3 phones then they should make the Note a "Pro" phone and stuff a 4000+mah 2-day min. battery and tout it as a super workhourse phone. But please don't go bigger to some ridiculous size and go 6'5"+ screens.