I wouldn't sell De Bruyne. No way. He's had injury issues this season but still delivered 15 goal contributions in 14 games. He's 33 this summer, but capable of playing on in my opinion. He either plays fewer minutes whilst others come through or evolves his game to play a more controlled role.
We can easily sell other assets and bring in money to replace him.
It's a shame we didn't/couldn't buy Paqueta instead on Nunes in the summer, I think we'd be in a lot better position now if we had. But as things are, despite things not going quite to plan we're in a great place to challenge for the big three trophies yet again.