^ It will take some time building a tier-1 team but it is inevitable that Newcastle will have one of the best teams in 2 or 3 seasons. Yes as you said, they might not go all the way in the next winter transfer window, maybe they will buy some average players and finish this season at a decent position, and then maybe from the start of the next season they will go all out in the transfer market. I guess this is good for the league as we now have one more better team to compete for the title. But I don't know maybe the league organizers have some restrictions or not on how much a club can spend each window.
If it is true that they are investing 200 million dollars in the next transfer window they can buy some very good players and offer them very high wages. They already have a good attacking team if they got better defenders they could challenge for European football by next year. The year after I think we will see them as a top 4 team if they are allowed to invest 200 million dollars every transfer window because if they are they could have invested close to 1 billion dollars by then because of the january transfer windows. That spend is only rivaled by Manchester City.
I think they need to get new manager firstly before have planning who the next player when window transfer opening, I see many available and star player could be option for Newcastle United, I heard they ask Manchester United to get Anthony Martial after his player not become regular position on Manchester United, beside Martial Newcastle can get Donny van de Beek because this player not on strategy for Ole in Manchester United, but all player depend on who will be manager for Newcastle, will Conte or Lampard still not any club right now.