Some points.
1) I'll wait until Ford actually releases the car. The rest is speculation and for the life of me, I don't know why "we" play this game with the manufacturers about what's coming out. I guess its to protect sales of existing inventory on the lots.
2) Just about any modern engine can handle boost. Certainly moderate boost with a fat tune (which is exactly what the manufacturer always does). They may upgrade internals just as insurance, or if they want to go smaller displacement and still big power, but the voodoo engine can handle MODERATE boost with good tuning. The reason our cars aren't all that great for boosting is the factory compression ratio, which is high for N/A output. That's solved easily enough with dished pistons and or hogged out combustion chambers on the heads (to save retooling for Ford).
3) If Ford wants to make a fight of the competition in the Hellcat segment, I suspect it won't be the voodoo engine. The Hellcat isn't a track car, it's a muscle car. I could see them twin turboing a coyote or the "aluminator" and put out North of 700 ponies, but I'm willing to be if they do that, it'll be a muscle car and not a track car. It'll assuredly have a single rear "live" axle.
The only way Ford could offer a 700+ car with warranty straight from the factory is to spend more and beef up the rear, transmission, clutch, etc. I'd be less concerned about the small block internals and more worried about other failure points of the vehicle (which is certainly what Ford bean counters will do). It's a delicate dance between performance, reliability and cost.
"You can have it cheap, you can have it fast, you can have it reliable. Just pick any two."