Video
He could escape or had help before the explosion.
A good introduction, if they want to bring Han back, would be to start off the next movie showing Lucas Black dealing with the events of Tokyo Drift, showing him having
Then you follow a few flashbacks of Lucas' life after the events of Tokyo Drift to see what he's done since then, as well as his present day doings.
After that, one night he notices a hooded figure following him and before he can confront him, the person disappears. He gets the feeling that the person knows something about Han and suddenly he begins questioning whether he really saw Han die in the explosion or not.nightmares months or years after the explosion.
Cue Lucas reaching out to Dom to ask him for his opinion. Dom tells him that he's just seeing things and that Han really is dead. Lucas sees the person a few days later again but this time he manages to chase him down. The figure falls over a railing to reveal part of his face, showing that he looks like a disfigured Han. Lucas calls Dom again and says he's sure he's alive, and in comes the rest of the family for the 9th movie.
Unfortunately, as it turns out, Han was kept alive by the movie's main villain and had a chip installed in him that brainwashed him. So the entire movie is the family fighting and avoiding Han as he is being used as a proxy by the real villain to do the dirty work, similar to the Winter Soldier. Then the movie ends with the real mastermind being taken out and Han snapping out of it to return to the family.
GOD DAMN IT I WANT IT
Doing this to any other character in another franchise would sound ridiculous, but since this is F&F, it's not farfetched at all.
Han surviving the explosion can really be explained away in the same vein as the Winter Soldier.