When it comes to Newcastle there is a big potential in them to finish their group stage even as leader. Because we must have all watched how they demolished PSG not much time ago. 
Despite Milan's high dominance in San Siro Newcastle managed to resist them and get that one point also.
Truthfully I think the matches against Dortmund will also go really well for Newcastle. I think they can get at least 4 points.
I think Newcastle will lose only once in Group F and that will be against PSG away.
Newcastle is in a great position to accomplish this as they will face Borussia Dortmund twice in a row, if they can win their first game at home then Borussia Dortmund will be basically eliminated from the competition already and they may decide to give up completely on it on their second match, making it even easier for Newcastle to get a second win, leaving PSG and Milan with only one remaining ticket to the next round. Despite Milan's high dominance in San Siro Newcastle managed to resist them and get that one point also.Truthfully I think the matches against Dortmund will also go really well for Newcastle. I think they can get at least 4 points.
I think Newcastle will lose only once in Group F and that will be against PSG away.