Maybe I'm a little late hearing this news. But will he splurge with unlimited funds for the club? Seems interesting to wait. If that's true then there will be a change in league dominance the following year. But for 7 games they are winless they are in the relegation zone. They should currently be struggling to move up and be in the middle of the table so that after the second half of the season they can be easier to rank better than at the beginning of the half season.
I don't think they will move so quickly to overhaul the whole team because it will definitely deal with FFP. They should be able to do it gradually without rushing and one of the most appropriate steps in my opinion is to bring in a new experienced coach. I'm quite curious which coach they will bring in to improve the quality of the team in the next few season, that's the most important thing so far.
^ 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.