Disagree with that. Potential replacements for Hazard & De Bruyne include Mertens and Carrasco (although he plays LWB atm), top notch players. The defense has lots of individual quality with Alderweireld, Vertonghen and Meunier (Kompany is a complicated case, but potentially a quality CB). In CM Nainggolan can be paired with one out of Witsel, Dembele, Fellaini, while Tielemans is waiting as well. The GK is world class.
In terms of individual quality, this team has everything a coach needs to succeed. Matching CF and the creative department is a problem in my eyes, but Lukaku nevertheless scored a lot after the EUROs. So to me it's definitely up to the coach to create something out of this.
Edit:
Ah no, that takes it a bit too far.
Courtois is better than Leno.
Meunier is on par with Kimmich
Alderweireld is on par with Hummels
Vertonghen (and Kompany if fit) is better than Höwedes
Nainggolan (and Dembele) is better than Khedira
Carrasco is at least on par with Draxler
De Bruyne is on par with Müller
Hazard is better than Schürrle
Lukaku is better than Gomez
"Better in every position" might be a bit OTT but we certainly don't have a worse squad individually. Meanwhile, they always look like a well oiled machine and we keep struggling to break down defensive opponents. It's very frustrating, and we're wasting a superb generation that has played together for over four years because of inept management. Preud'homme should come in and make something out of them before it is too late.