"challenge is at the core of Souls games and cannot be replaced."
It really just cannot, and that is what has made these games so special. The games require YOU to be the one that figures out how to beat the game, not the other way around, as most mainstream games are nowadays. This does not mean that the game requires you to develop near God-like skill at the game by the end, or even anything like that (that is Sekiro's deal). While this is a totally valid approach to the games difficulty, it is not the only way. You can get help, farm for souls and/or upgrade materials, or even get particularly powerful weapons (like the Drake Sword, BKH, Rapier, or Broadsword). You can explore other areas, such as going to the painted world before O&S, lower undead burg before Gargoyles, or going down a Lord Soul path suitable to you.
These games are all difficult, but they are also all fair (most of the time), and reward ingenuity. Elden Ring merely takes this to the next level, as open world games usually do. But this is going to take it further that any ordinary open world. Rather than taking a few side paths at the beginning, and then becoming powerful enough to take on the rest of the game, Elden Ring's above average difficulty will (might, I really don't have enough information to be positive) push you to take every possible advantage the whole game through.
But, I hope he sticks in a mega hard level with an insane boss at the end for those diehards out there, myself included.