I can imagine a lot more "COD" via Direct Deposit...

Dumb move. Just because you're dominant doesn't mean people will flock to you by default. eBay's market position was built up partly through ease of use. As Burn alluded to, it's the more casual users who will just abandon eBay.

Personally, I normally purchase stuff from overseas anyway, and use PayPal for that. But I'll use eBay Australia even less, because the number of casual sellers will drop (and the scalpers/most dealers on eBay Australia are of no use to me).