Kuroo has a lot of amazing character depth, but he doesn't actually have much character development* OUTSIDE of that backstory of him and Kenma as kids. He had his development prior to Haikyuu. Instead, he became someone that plays a role in aiding other characters' developments.

We can also see that his motivations for improving was always to be able to continue playing, to fulfil his coach's wishes before he retires, to just feel good about winning for himself and for others, as a team. But it was never about being the best at it unlike Hinata, Hoshiumi

Kageyama, Oikawa, and everyone else who did end up becoming a pro. So Kuroo being someone who essentially promotes volleyball, is the perfect summary for his character. Now he gets to show the entire nation, even the world, just how amazing volleyball is.

I would also like to point out that this call back to Coach Nekomata had me sobbing. That was the moment Kuroo's interest for volleyball rapidly became love. He showed Kuroo that ANYONE can play volleyball, which is significant to how now he wants to show Hinata off to the world.

Kuroo's character had always been about his love for volleyball. From the very beginning to the the very end, literally. He's an extremely consistent character, more than just his looks and witty antics. I'm so proud of him. Thank you Furudate for such an amazing character.