UEFA haven't ruled out the possibility of Barça-Napoli being moved to Portugal. According to 'O Jogo', the European governing body has already sounded out two possible stadiums if the COVID-19 situation worsens in Barcelona.
The quarter-finals, semi-finals and final will all take place in Portugal anyway so adding an extra match won't be an issue. The same report claims UEFA are ready to hold Barça's Last 16 match in either Porto or Guimaraes' stadiums.
As things stand, UEFA - via 'O Jogo' - still expect the match to take place at the Camp Nou.