I doubt it will over take it by 2016. But it will definitely cause them a lot of headaches going forward.
Lol... that should be the case. Personally saying, I am not too much concerned whether Bitpay will overtake PP or not (although it will be really good if it happens). If PP reduces their fees in order to be competitive against Bitpay, it will be a great victory for the digital currency.
Paypal is incredibly convenient and almost universally adopted by the main seller sites online. I know that I myself love Paypal to death and cannot imagine online commerce without it. I think it will be much farther than 2016 if ever.
It'll be interesting to hear your opinion on their fees and other charges.