Let's wait for 8.10 to land instead of making assumptions.
I understand everyone's being anxious about the changes and loves to theorycraft and play with numbers and all. Everyone wants to have a grasp on what is gonna happen in the next big patch, maybe even show some flaws in the numbers etc.
While I enjoy reading about the numbers and trying to find out what the changes will bring, I'd like to say that it's safer, for the moment, to wait for the changes to land. Some maths are fine, but people are already calling this update bad, that it won't hit the mark etc.
There are SO MANY changes coming up, that you can't know how they will land. For example, you can't possibly know how the extra gold needed for the IR or Zeal item will affect the pace of the game. You don't know how the 2x BF sword will affect your early laning, how you itemize before completing an item etc. There are a lot of variables that can severely change how the early to mid game is play; heck, we might even go back to rush BorK meta, seeing how it's 200 gold cheaper.
Nobody can know how things will play out. Let the patch go to live, let people play with it, test out all different champions (marksmen or not) and we can discuss later about numbers tweaks.