I am not going to review the transcript, but I am nearly 100% certain that if you watched the keynote, it was stated explicitly that it would be available later in the year. Sure, that could have meant one second after the keynote ended, but if you thought that, then I have a bridge in Brooklyn to sell you as well.
As for your situation, wouldn't you rather they get this product right and properly approved, rather than just getting it so you can compare it to your doctor's (likely) more accurate reading? This is not a functionality that I want them getting wrong and I doubt you do, either.
[doublepost=1543244778][/doublepost]
I can virtually guarantee you that you're not going to see this on 12/31. That was hyperbole. They do have approval to market the feature, but if I read the approval letter from the FDA correctly, they still had to provide some data as well. The functionality (mechanically) is already in the Series 4 Watch. They just need to flip the switch (or provide the app) to make it work. I'm sure they are more eager than you are to release this feature. But as I said in the other post, isn't this something you'd rather they got right, than rushed to meet an arbitrary deadline?