I do not understand your argument as the parent post is saying the PS5 can play PS4 games. So the PS5 will also benefit from the great games coming on PS4. The prices of the games would be the same, you would benefit from the same experience of the devs developing on the PS4. The only disadvantage is that the PS5 will be pricer. And it will also be less ecological-friendly if you intend to buy an used PS4. But that's it.

Should be, at the end of the day they are both just X86_64 systems. It isn't like the console generations of old where each one would used a specialized CPU usually designed specifically for that console. (The PS3 had to include a full PS2 chip for its compatibility layer)

All that said, I do see them somehow screwing it up.

For me, I'll get a PS5 for Demons' Souls alone. When you factor in upcoming games like the new Horizon Zero Dawn next year and the graphics-upgrades like Cyberpunk 2077, its definitely worth it.

Although, realistically, it'll be a few months into next year before I actually get one.