Because of the fact that bitcoin is a competitor to PayPal and the whole fraud issues, it would be an immense hurdle.  But, imagine if PayPal finally accepted bitcoins..hell they could even set up their own exchange that would compete with other exchanges, especially localbitcoins.  PayPal could use their own block chain technology.  It would increase the market cap of bitcoins and Paypal.  One can only dream...

 PayPal is going to have to adapt to blockchain technology some time or it will become obsolete.