> But a high quality automatic LOD at build time may (read: almost certainly does) strike a much better balance for both current and near future hardware
You can't have a manual LOD for a cliff where half is near the player and should be high resolution, and half is further away and can be low resolution. Nanite's hierarchical LODs are a huge improvement for this.
You're also underestimating the amount of time artists have to spend making and tweaking LODs, and how big of an impact skipping that is.
This is assuming you have this "one big cliff mesh". This is the Nanite mindset: Just let the artists throw anything that comes out of their DCC at it. That is a great value proposition for studios, especially the ones that fail the marriage of art and engineering.
It's a bad value proposition for end-users. Nanite is much slower for the same image quality that a bespoke solution would offer, which is evident with several AAA titles that choose to use in-house tech over UE.
You can't have a manual LOD for a cliff where half is near the player and should be high resolution, and half is further away and can be low resolution. Nanite's hierarchical LODs are a huge improvement for this.
You're also underestimating the amount of time artists have to spend making and tweaking LODs, and how big of an impact skipping that is.