I imagine the shipping issues will be similar to the global shipping: you are responsible to get the card to CSG, while CSG/eBay are responsible for final shipping.
The interesting thing will be not as described claims after this goes into effect: does the buyer get three days after the item has gone through CSG to then make a claim? Does the CSG thing void the return claims window?
Part of it is also schoolyard rules: punch out a bully or two and the rest go away. eBay has so much fraud and so many item not as described claims that it is trying to send a message to fraudsters: go elsewhere. If it can stop the dozens of fake Wagners, etc., that are causing these claims it will save money in the long run, even if it doesn't end up making this 'free for now' service a 'fee forever' service later. My prediction: a policy where a seller who accumulates a certain # of CSG denials will be banned from the site.
That said, authenticating slabs is over the top. A bit of:
Paul is spot-on: if eBay raises fees or passes through this cost directly to sellers, a lot of them are going to say the hell with it and consign to AHs instead.