I'd be interested to hear what everybody's wish list would be for their ideal F&F ride.
If it goes into the MIB plot, story and location can be anything. It's not bound to the location like Supercharged was to San Francisco.
Something similar to Mario Kart or Test Track is going to be the obvious ride system. Using the patent for drifting would also be a nice addition. For a ride based on fast cars, you're going to be expecting to be in a car. Doing something similar to TT/RSR isn't going to be enough, it's going to to have to best it. Theming wise, it won't beat RSR but it can improve on the racing aspect. It's going to have be fast, it's probably going to need to be the fastest ride in Orlando.
To go fast enough, it's going to need to go outside.The plot of land next to MIB is obviously valuable so raising in the track up above could work and will give enough room to go fast enough.
I would theme the outside part to a highway with trees either side. I'd put the maintenance bay outside like an off ramp, maybe theme it to a gas station. For the on ramp afterwards, you could fake out a truck coming up ready to enter the highway.
For the straight section nearest Portofino, I'd have the track go into tunnel for noise suppression. Base it on the Griffith Park Tunnel as a nice tribute to BTTF.
Near the end of the outside section, have a highway sign pointing towards Universal Studios. Basically a real life version of this meme:
Storywise, it's going to be basic cookie cutter. You go into the building because Dom is throwing a party because family. Maybe it's his son's birthday party, who knows. Dom promises us a race but before we can, Charlize Theron's character shows up to ruin the day and we have to escape. Luckily Ludacris's character can control the car (Another BTTF reference) we have to escape in because obviously he can. We escape, baddies chase us, police show up, we have to escape them. We think we're safe when Charlize Theron's character takes over control of our car and before she can drive us off a cliff, Ludacris manages to gain control again and we're safe once again.
Similar to RSR, another car shows up besides us as the track splits into two and we race on the outside part. The person in the drivers seat has a red button (A MIB reference) for NOS and the first person to press it will win the race.