I don't think that Paypal will integrate Bitcoin in the near future. But I can see Ebay adding a Coinbase / Bitpay option very soon. During the past 2 months or so, a lot of mid-level and small-level merchants has started accepting Bitcoin payments. Ebay won't be able to ignore Bitcoin for too long.
I think the opposite. Paypal and Ebay working together. If Ebay accept bitcoin directly, Paypal's endorsement will be reduced. In my opinion there is the only way that if Paypal accept bitcoin as deposit method than you can shop in Ebay via bitcoin indirectly.