Newcastle are a small team but they are performing well. As their team is getting stronger day by day, I think adding some young fast players to their team will give them great progress. On the other hand, if Harry Kane is transferred to another club, Tottenham will have some adverse effect on their team.
Not anymore, Newcastle are a big team right now although they haven't proved anything in many seasons. Newcastle have been impressive during this season, no one will underestimate them in the league as they have really improved a lot. So if you think Newcastle is a small team then I hope you are willing to watch some of their match later.
Newcastle still don't have a world team, but they are good enough to finish in the second tier of England. They won't be 3rd this season, but I don't think that's the goal either. They just want to finish with the best 6-7 and then hope that they can bring in some reinforcements again next season. They have so much money, they can pay every player in the world and they can pay all the salaries as well. Mbappe wouldn't be a problem either, but the problem with very good players and stars is that they have little interest in playing for Newcastle United. Of course, PSG and City also started this way.
It took several seasons for Newcastle to be able to get several star players to strengthen their team. They could start by recruiting old, experienced stars for a short period and keep at it until the team gets stronger. But for now, it is difficult for Newcastle to convince players of the class of Mbappe to play with them even though they are highly paid.