I believe losing Elanga to the NuFC is a big blow.
It is a big blow losing him, because he is an important player, but it is also very good business for Nottingham Forest, they signed Elanga from Manchester United for only £15m a couple of years ago, and now they are selling him for £55m, now i say that is very good business, they could use that money to get two decent players.
Newcastle are back in the Champions League, so they need reinforcements, and i am pretty sure they are not going to stop here, i expect them to have a pretty busy transfer window.