As it stands now... the 7.3L engine is "designed" for SuperDuty trucks. "Designed" for towing not high speed. As it is "designed", it is not a candidate for the Raptor or Mustang.
If it was offered as a Raptor option, would you even want it in its current configuration? The only gain would be V8 sound... the HP and TQ will likely be near that of the current 3.5L HO, but weigh much more (+300lbs at least).
The 5.2L is the real candidate for a Gen 3 Raptor (in 2021-2022). Probably a NA base engine making close to current power levels with a Supercharger option above 600HP/600TQ.
I would absolutely want it. It offers a hell of a lot more than sound. It's got reliability, durability, and, more importantly, it's got serious power potential. Can you imagine what that thing will make with some headwork, a cam, and a big Whipple?
And what makes you think it will weigh 300 pounds more than the Ecoboost?
Also, what is the weight of a fully dressed 6.2 vs. a fully dressed 3.5? I've asked many times but I don't remember ever getting a solid answer.