Actually no. You are right though - I've never coded assembler on either x86 or ARM. However, I have coded for Z80, 68000, PowerPC 601, PIC, and AMTEL chips.
I was referring primarily to branch-prediction and other instruction hints. They were pretty modern by the time I left commercial assembler coding. But I'm not too surprised if they are no longer used. I'm just older than you. That's all.
However, and this was my point regardless of your flame, you would be a total fool to attempt to write a modern operating system in assembler, unless it was for a particularly niche purpose, and even then I believe you would be better off writing a compiler for your environment.
Compilers are hardware domain aware, whereas coders are problem domain aware. This means that compilers are really good at dealing with the machine-side of things, but they won't compete with a coder when it comes to the problem domain (and I'm not talking about design patterns here). It will take a long, long time before a computer turns around and says "You don't need to software for this at all - just use a simple hardware system".