this is a bit weird to say though. PayPal is not a merchant to accept bitcoin but they are a service provider that has been providing payment services and online wallet option to people. now they have added the option to work with bitcoin too.
the way i see it this is another way for them to make more money from commissions while keeping their users and won't affect adoption of bitcoin.
Paypal will have many more advantages and paypal will continue to be used. Cryptocurrency users who previously did not have a paypal account will certainly create a paypal account to be able to use the service. This is a new breakthrough made by paypal. Apart from bitcoin, several other cryptocurrencies will be added such as ETH, LTC and BCH.
When making payments using virtual coins such as BTC and ETH, paypal will convert them into the relevant national currency, so that companies providing goods and services are still paid using the national currency but with pre-converted cryptocurrency intermediaries.
Paypal is a tranding topic today. this is the beginning of the mass adoption of Bitcoin and of course there will be more to come.