No way, Newcastle will have to aim to the top - it's way easier to get a good manager to commit to the club than a good player when the team is bad. Fonseca has shown some good patches as a coach but I highly doubt that he's the kind of profile that Newcastle will be looking at.
I know Newcastle are now rich, but it still doesn't automatically make them a big club, I understand your point and I'm pretty sure Newcastle will hope they can start buying world class managers/players, but that would not happen immediately, they'll have to start from somewhere, just the same way other clubs which experienced take overs by multi-billionaires did (City for example), they will still buy and sack a couple of managers before they finally get it right, so Fonseca might actually be a good option for now, mind you that they do not have the quality of players that can attract a world class manager as of yet.
City again with 3 goals tonight...
The interesting part of City's impressive goal scoring form is that for the most part of last season and thus far this season, they have been lining up without an orthodox striker, that's amazing and I'd not be surprised if they do not go after any striker in the January transfer window.