Ebay and Paypal signed a contract that Ebay has to use Paypal as first payment option for at least another year after the split. Thus, after that year Bitcoin could be a serious option.
They would need something that is publicly accepted, understood and easily available. Unless some major changes will happen in the following year in the perception of Bitcoin I would doubt that it would be considered as a "first payment option". Maybe accepted among other things yes, but credit card payments, continuing with PayPal or something along these lines is more likely.
