The wizarding world would be in shock. The Malfoys are known for their dislike of the Potters, so Draco saving Harry would go against the family's reputation. It could lead to Draco being ostracized by some in the pure - blood community.
The Dursleys might face consequences as well. With Harry being taken away by Draco, they could lose their connection to the wizarding world that they secretly feared and despised. And if Draco were to expose their treatment of Harry, they could face some form of wizarding justice or at least be shunned by those in the know in the magical community.
For Harry, it would be a huge change. He would no longer have to endure the abuse of the Dursleys. And his relationship with Draco would be very different. They might form an unlikely alliance or even friendship. This could also change the power dynamics at Hogwarts as Harry and Draco's new relationship would influence how the other students interact with them.
He could be doing it out of a sense of justice. Despite his family's views, Draco might see that the way the Dursleys treat Harry is wrong and decides to step in.
For Harry, his friends in Gryffindor could be a bit confused at first. They know Draco is not exactly a friendly character. But overall, it could lead to a more united front against real threats in Hogwarts. The teachers might also take notice. Dumbledore, for instance, would probably be proud of Harry for showing such selfless courage, regardless of who he was saving.
Some fanfictions might depict that the wizarding community might see her as a hero. However, others could show that she faces backlash from some conservative wizards who think she overstepped her bounds. They might try to isolate her at Hogwarts or spread rumors about her. But her friends like Harry, Ron and Hermione would surely support her through it all.
After saving Harry, Snape may have to deal with a lot of mistrust from some people in Hogwarts who don't understand his motives. However, he might also start to form a closer bond with Harry, which could change the whole dynamic between them. This new relationship could lead to some unexpected alliances and enmities within the wizarding world. And if the Dursleys were to try and retaliate, Snape would have to constantly be on guard to protect Harry from any potential harm they could cause.
One consequence could be that he gains an unexpected ally in Draco. Draco might feel indebted to Harry and start to change his views towards him, which could lead to some interesting interactions between them in the future. This could also cause some tension among their respective groups of friends.
One consequence could be that Harry becomes withdrawn. He's so used to the abuse that he doesn't trust people easily. He might have nightmares often, reliving the moments of abuse. For instance, if Vernon has hit him before, he could have flashbacks in his sleep.
They would likely face severe punishment from the wizarding world. The Ministry of Magic would not tolerate such blatant abuse of a wizard, especially one as important as Harry.
Maybe it was an accident. Like a wrong Floo Powder destination or some kind of misfired spell that landed Draco right at the Dursleys' doorstep just as Harry was there.
One consequence could be a change in the public's perception of Hermione. Some might see her as a hero for standing up against an unjust imprisonment, while others might view her actions as traitorous, especially if they believe Draco was truly guilty. This could create a divide among the wizarding community.
He could become very withdrawn. Since the Dursleys are constantly abusing him, Harry might start to avoid people and isolate himself even more. He may lose his self - confidence and feel that he is not worthy of love or respect.