Not sure where this is coming from but bitcoin has already overthrown paypal by market cap. Many many times. Now it's time to am for bigger challenges like currencies etc.
A 100 billion marketcap is huge but yet the beginning because adoption is yet to come.
With the increased price bitcoin has gone beyond PayPal in terms of market capital. In terms of growth too it has reached almost big through different accessibilities available. PayPal as an payment processor has gained good reputation and this will let the community grow as majority of the business people use PayPal for cross border transactions.