At Madrid, players are full and Bellingham might find some playing but there is no guarantee. Regarding Hazard, he is not performing so yeah Bellingham will also get the same tratment if he doesn't performs. I don't think it's only Madrid, there are many clubs who also bench players when they don't perform. Take Nunez at Liverpool for example or Ronaldo at United. The question is where he will find good amount of playing minutes. With Bellingham, I think he has better amount of chances at Liverpool rather than at Madrid.
Bellingham is only 19 years old. If Real Madrid want him, this young age is a big criterion. It could be a big name like Toni Kroos. He can be indispensable in the midfield. If he has to wait a few years for this, I think he should be patient. I believe he will work wonders together with Vini Jr. Dortmund presents another football player to world football.
Bellingham can be a long-term project for Real Madrid, he is still very young and his development is very good. The potential that Bellingham has can be developed with Real Madrid, Ancelotti can make Bellingham an ideal replacement for Modric who is not young anymore.
Trust from the coach can make him grow, he needs support from the coach to hone his skills to be even better. Dortmund once again orbited a young star after previously Manchester City felt very lucky to be able to get Haaland services.