Does anyone know if this GOTYE includes the post-update DLC featuring HD texturing?

Just confirming that this GOTYE does indeed include the HD Content Pack.

thank you.

Good to know, thanks for confirming. It also makes sense since it's a 54gb install lol.
.

how exactly have you verified this to be so?

On Steam the game is around 43GB and the HD Content is around 11GB .. so 54GB makes sense it is already included
https://steamdb.info/app/241930/depots/

Ultra quality textures load properly.

Because there is no Ultra setting for Textures under Advanced Options without the HD Content Pack installed.

The Ultra setting is always available, even if the HD content pack is not installed.
It is explicitly stated that choosing the Ultra setting will make a difference in VRAM usage and performance, only IF you have the HD content pack installed.
Now the problem I have is that I cannot get rid of the HD content pack in order to save SSD storage space.

ok

Sorry, I was misinformed. I double-checked the Steam version and you're right.

And the install without the HD Content Pack was 42 GB on Steam, so I guess that confirms it since this install is 54 GB.

No worries. :)
I run the game on a RX5700XT with 8GBs of VRAM and can confirm, for anyone still doubting it, that when switching form High to Ultra textures, VRAM usage goes from approximately 4GBs to approximately 7GBS.
So the HD content pack is definititely included, as part of the base installation.
Will post screenshots when possible, even though to me, the visual differences are too imperceptible to notice on a standard size FHD monitor.
There certainly are extra details, but I would have to go looking for them in order to notice the difference.

Cheers.