Newcastle is an example and we can see them last season and the financial capabilities they have made Newcastle manage to maintain at least the top five positions until the end of the season and that is influenced by the good squad owned by Newcastle itself.
They don't spend a lot of star players, but they have pretty good performances. Indeed, since the change of owners, Newcastle has become better, they have been shopping for players but not too big like Man United, Chelsea or other clubs. Although at first I thought they would bring in a lot of star players, but that didn't happen.
If it compares to Notthingham it might be different, I think Newcatle is more experienced. Nottingham may struggle next season, this is because many players will be leaving. As always, those who get offers from big clubs will tend to leave because of more salaries and bigger teams.
Newcastle is an average team in the Premier League that have fairly good players that is why they have experienced this level of growth so far. One thing that makes teams improves is having a good coach that can be able to manage the players in the team and develop them to be world class players and i think Newcastle's coach have been able to produce some quality players in the squad.
As for Nottingham Forest, they are still new to the Premier League with not much experience even though they have got a good run this season but there is no comparison between them and Newcastle because Newcastle is far more experienced because they have been around in the Premier League for a long time. If some of Nottingham Forest notable players signs for bigger club next season the club will face some problems but what will make some of the players to still remain at the club will be when they qualify for the Champions League next season.