Hi Yamen -
Foundation is now Flex first (version 6.4 released today)! With the latest 6.4 release the new XY Grid is the default along with Flexbox based UI components. Foundation 6 always had a flexbox grid but this new XY grid is killer because it does vertical and horizontal along with margin-padding control. You can learn more about it and join a free webinar to learn it here: zurb.com/blog/foundation-6-4-a-new-grid-javascrip…
We're SUPER excited about CSS Grid and have already started using it. Foundation 7 will be released November of this year so we think the browser support may not be there for CSS Grid by then (Foundation is moving fast). We have already built some of our Grid with CSS Grid and experimented with it's potential: http://zurb.com/playground/css-grid-examples
Foundation 7 roadmap is coming soon so watch the Blog and Follow us on Youtube for that!