I believe Newcastle cannot build their dream team as quickly as turning the palm of the hand as they will have to adapt over several seasons to attract top players. One of the most decisive is the presence of a top coach at Newcastle and if they already have it then it is not impossible that some of the top players are currently willing to work with them.
There are many barriers for their dream.
- The European football now have a few rich clubs: Chelsea, Manchester City, PSG rather than only Chelsea 10 to 15 years ago. So now Newcastle will have to fight with other rich clubs to buy best players.
- Currently they don't have a good team which is reflected on their results so that star players will hesitate to join them. It is very different than Chelsea because under first years of Abramovich and Ranieri, Chelsea are in top of Premier League and have some good achievements in Champions League as well. Manchester City did not stuck in delegation area like Newcastle now.
Apart from that I also don't think that the money they invested in buying some players will be wasted this season because they are players who are expected to help the team stay in the Premier League next season. Newcastle will certainly have to be careful with transfers if they don't want huge losses should they have to fail in the end. There are 17 more match for them left this season so let's see what they do.
Newcastle will have to sacrifice 2 to 3 seasons to build up from scratch to above average then moving higher to top clubs of Premier League. I meant this period might take up to 5 or 10 years. It does not easy to achieve because all above reasons or even more reasons.
Another bad barrier for Newcastle is more strict regulations on club finance and transfer balance than easier ones around 10 to 20 years ago. So even Newcastle are ready to spend huge budget for transfer and salary, they will have to do it slowly and less seriously than what Chelsea, PSG, Manchester City did years ago.