I believe this is good if Rockets wants an immediate result since those 5 2nd round pick is still need a lot of years to develop without any certainty of success.
Rockets already have a solid starter while Green and Brooks game is not that consistent and impactful. They are building around Sengun so adding Durant will make Rockets formidable next season.
They just need to work on their bench and they are good to go.
If Jalen and Brooks were just consistent, I don't think that the Rockets will replace them. But you're right, they want to build their next roster around Sengun and adding Durant looks good on it. They've got their respective roles to play with and also Steven Adams. Two towers for the Houston Rockets with Durant on the outside making plays together with Vanvleet. I've read what Jalen Green said about this trade and it was a broken heart for him and blames the stint that they had during the playoffs, he's not expecting this.