do we still need deb videoimprovevero49 main in the sources.list for the latest 18.9 image to use the new kernel?

Well if you already have installed the Kernel you can remove it. But yes if you have install the latest 18.9 Image and want the kernel then you need that line.

if i remove it then i will not recieve kernal updates correct?

has the 4.9 kernel been merged into mainline for 18.9?

No - but the newer kernel will come with v19.

So those of us that are staying on 18.9 are SOL?

No - you can still get a 4.9 kernel up with v18.9, but it won’t get any further improvements now.

The future is Kodi v19.

I understand kodi 19 is the future, but since most plugins are missing from the official repo, and others are broken… im gonna stay with 18 for a while.
I was just curious if the 4.9 kernel was going to be merged with 18

v18.9 is end of life – so from an official support perspective, it only shipped with 3.14.