Indeed , given that you will no longer be able to break quests by using mark/recall and levitation the sandbox feeling is severely reduced . Options will be limited so the weak aspects of the game are masked .You start as a dragonborn and there is nothing sandbox in that .
You get unique shouts
You get to destroy the economy.
You get to hunt deer.
You get to kill dragons.
Yo get to fish.
You get to have relationships with NPCs.
You get to dual wield different types of weapons.
The map itself is in 3d.
There are tons of dungeons as they said themself.
You can work as a NPC and just forget the storyline.
You can be anything.
So how isn't it a sandbox game.
Do you think fighting is not sandbox material.
Go ahead and use the illusion spell on foes and go about your business.