so everyone accepting paypal is actually not accepting $, or any other fiat currency?
Of course. The currency that they accept is one thing, the means through which they receive the currency is another thing. Last time I checked, Dell USA accepted only dollars, but you could send the dollars in one of several ways: PayPal, credit card, bank wire, old-fashioned checks, -- or BitPay. Likewise, Dell would pay refunds only in dollars, even if you paid with BitPay.
what happens when paypal will integrate btc this year? still nobody accepting bitcoin?
they do accept bitcoin as payment, the just dont hold it.
Either PayPal will do the conversion to dollars and send dollars to the merchant, like BitPay does; or most merchants that accept payment via BitPay will not accept bitcoins through Paypal.