thanks late-1960s car advertisement but this is 2020
i do believe that ford may eventually shoehorn a large v8 into the raptor but only to appease the substantial demand for it and to blow the TRX out of the water. if they offer several options the v8 would easily jump past the $100,000 mark after dealer adds. you and everyone else begging for a v8 going to ante up with an order for a six-figure raptor?
It would cost Ford jack shit more to make a TT V8 than it does a TT V6. You realize they make these engines right? They don't buy them.
At some point, the 3.5L will not make enough HP. When 800 HP is the starting point to be competitive in eh full size off road truck market, Ford will need more displacement to do that on pump gas. Octane is the ultimate limiter. You cannot keep upping the boost to make more power once you hit the limits of the fuel. That is why there is no replacement for displacement. EVERYTHING a small engine does power wise, a larger engine configured similarly does better. N/A? check. Boosted? Check. Nitrous? Yup.
The only thing a TT V8 would significantly drive up cost to Ford is a stronger drive train behind it. They would need to upgrade the 10 speed in house, and then go source stronger T-cases axles, driveshaft and u-joints. Given everyone is consolidating axle suppliers now- I think there will be something ready to go for those power levels for all the OEMs to choose from.