We know that Samsung is not limited by carriers, especially here in the US with models like the Note 8 SM-N950U1, since they released the original OneUI 1.0 beta to carrier-unlocked models here in the US before any of the carrier models got it. It's also not a snapdragon issue since the Hong Kong Note 8 uses a Snapdragon 835 and has an unlockable bootloader. Not only that, but XDA has already made custom ROMs based on Android 10 for it!
I love my $1000 Note 8 and I don't want to upgrade, but getting security patches is important for me and KNOX won't suffice for less frequent security updates in a year. I don't want to be that guy, but if we don't get an unlockable bootloader on US carrier-unlocked models, I'll be spending $1000 (or maybe less) on a non-Samsung phone that I can unlock the bootloader on to keep receiving security patches (or pushing them to my phone myself if I get into custom ROM development).
No excuses, Samsung. My Note 8 was a $1000 phone that came out with Nougat literally a week before Android Oreo came out. The fact that you're counting Oreo in the two year update guarantee is wrong, but the fact that you won't let me unlock the bootloader on my $1000 pocket computer to allow me to deal with updates myself (even though you let others outside North America do it, even if they have Snapdragon SoCs) through custom ROMs is even more wrong.
Now I know the typical responses. "Samsung would never do this," "why would they want to do this," etc. Here's the thing: Samsung only has things to gain from this. Unlocking a bootloader and installing a custom ROM is far too complicated for most users. By allowing for an unlockable bootloader on US carrier-unlocked models, Samsung could take a chunk out of OnePlus' market share among developers in the software development powerhouse that is the US.
Plus, let me remind you, Samsung has unlockable bootloaders on their non-US carrier-unlocked flagships, including their international and Hong Kong S8 and Note 8. Samsung so far has not been able to make a valid justification for why they cannot do this on their US carrier-unlocked models.
And as for the rest of you with newer US carrier-unlocked flagships: you will be in the same boat in a few years, missing out on the latest Android version (if you are a developer, this is a major problem) and missing out on frequent security patches soon after. It is within your best interest to support this demand.
I hope some kind of exploit comes soon, currently running Android 10 on my Galaxy S5 with LOS 17, and it runs amazing. But the only reason that's possible is because you're able to flash back to KitKat with combination firmware and run TowelRoot to then flash TWRP from a Safestrap. With the S8, Samsung has prevented Android downgrades. Kinda sad that it's been this way for a while though, it is so simple and easy to unlock the bootloader on so many other Android devices out there that are way smaller than Samsung. Really considering leaving Samsung for my next phone so I can go back to being a power user with my primary phone. Sucks that Samsung makes such beautiful, good-looking phones, but such bad, bloated, and locked-down software. Although they have stepped up their game with One UI, I have to admit.