Seriously? Who would even want to make the movie at this point. If I was Diesel, I'd just say it's over. My best friend dies in a car wreck while a movie about cars we're making together is in production so now they have to figure out what to do with his character? Fuck that noise. Close production. Eat the loss of revenue and move on to something else. Doing anything else would be epically tasteless and beyond lame.
Kill his character off-screen? Tasteless Fail
Happy ending off-screen? Lame Fail
Recast and reshoot? Epic Fail
Kill his character off-screen? Tasteless Fail
Happy ending off-screen? Lame Fail
Recast and reshoot? Epic Fail