They sell just fine because of the marketing trickery. However, I am not sure can afford the warranty side. Many of us have cam phaser rattling engines, plus there was the plastic oil pan dilemma, and then the updated valve covers, and the list goes on. Based on what's happening, that doesn't sound like a winning, money making approach. Based on the articles out there, the only place you will get a 3.5 ecoboost going forward is some f150 (non-raptor), and the expedition and navi.
LOL - I'm a GM guy driving a Ford now & this makes me laugh my **** off! Hhahhaha - dude, people go on forums for a handful of reasons, one of the most prolific being shit talking and/or troubleshooting an issue w/ a vehicle. Ford sells more of these engines than anything else, go on to Tundra/Ram/GM truck forums you'll see all kinds of issues & complaints that'll make you think nobody can make a decent truck these days (well....that's sorta kinda true, let's just say they're all a little imperfect eh?)
Every damn lincoln has the 3.5 ecoboost as an option it seems, I suppose you're forgetting the relaunched Aviator running same powertrain as our Raptors?
Regardless - just like I said previously, I am extremely confident should Ford actually bring this to market they'll price it as a halo type vehicle no different than a Trackhawk, M car, Hellcat/Demon, etc. & just like all those other brands they'll offer a less extreme/lower powered version w/ the same idea. Moves more units makes them more $$$$ The market for a 450hp 15mpg $60-75k truck isn't huge, but its decent sized - the market for a 700hp 10mpg super truck? Not so big.
As far as "not being able to afford the warranty side" - again, you need to experience some other brands. GM produced a 5-6 year run of trucks they KNEW had vibration/NVH issues, they KNEW had a "patch job" tranny that was only temporary, they KNEW had high AFM/lifter failure rate, they KNEW had torque converter problems & they 1000000% KNEW/KNOW that EVERY single truck built in the first 3-4 years of that model run had the wrong type & amount of tranny fluid. They just sit on their hands waiting for warranty claims & mitigate them as much as possible. I had 3 of em.
Let me ask you this, if you were a business owner. Would you rather sell 300,000 3.5 EB Raptors w/ avg. MSRP of $66,000 or 50,000 5.2 super Raptors w/ avg MSRP of $80,000?
The delta between what people would be willing to pay & what they could charge for a 3.5 vs. a 5.2 is too great. There is NO WAY they won't jack the price up big time & no way they could ever entice enough people to part w/ that kinda money for what is essentially a "super truck" toy that brings "impractical" to a whole new level.
You know what the best selling truck is in China (now the largest car market in the world btw)? Its the Raptor. You know what WONT be the best selling truck in China? A 700hp Raptor. They'll still sell em for sure, just not @ the same kinda volume. No where near it. I've been to China 4x - every time their middle class gets bigger, they want more luxury items, but there's no getting around the traffic & fuel/insurance costs (plus govt regs for engine size) - these are probably things you didn't consider. But consider this - Mercedes sells plenty of S class sedans in China too - but they're equipped w/ 6 cylinder engines.
They will continue to make the HO 3.5 & will produce it alongside the 5.2 if it ever comes to fruition. It's all about marketing & moving units - it sounds messed up, but if there wasn't a Mustang GT, you could only go from turbo 4 to a GT500 or 350, Ford would have a much harder time selling the GT500/350 @ the prices they do. Likewise, the incentive to "step up" & shell out big bucks for a 5.2 Raptor will be less when that's the only one available, you can charge more when you have a "B model" cost of entry.