Given the reaction to the previous post regarding Marco Verratti and a highly unlikely transfer to Chelsea, the prices quoted by Italian sources for the PSG midfielder probably won't be considered too outrageous.
Given that Verratti would conceivably take Cesc Fàbregas's place in the squad, that part of the rumor is plausible. The €50m cash portion isn't all that outrageous either (barely half a Pogba!), especially in today's transfer market and especially considering that Verratti is still just 24 years old (and barely so, having just celebrated a birthday last week).
The less plausible part of the rumor is that it's a part-exchange player swap proposition and those sorts of trades are highly uncommon in football. And the original sourcing of the rumor is Mediaset Premium, who are notoriously silly even by Italian media standards.
Still, the price smells right, should the opportunity ever present itself.