I am wondering with the congestion issues and surge of popularity if Square Enix may suspend all preorders of Endwalker at a certain point to prevent complete chaos and limit Early Access entry?

I would say preorder now just to be safe. I feel this surge isn't going to end and that people are going to be primed and ready for November 19th. I think crowd mitigation measures may be needed and suspension of preorders seems like a likely scenario.