Inside Unreal: New World Building Features

I have a question about “vertical streaming”, i will reword what i asked in the streaming chat to be more specific, for what i understand when i load a world cell all the stuff inside that cell will be loaded, so, if in this cell i have a building with some floors and all the floors are streamed one by one with the old level streaming system i wonder if the world partition system will override it and will load all the floors at once or it will load only the first floor and keep the old system for the others.