Just to share my theory on How I Met Your Mother, so I can say "I knew it!" (or not): Barney Stinson is dead! I know, quite shocking, but it all makes sense if you think about it.
First, Barney is never shown in a future scene, nor in any kind of special moment with the kids. He is always this guy who lives hard, taking life to the extreme, and maybe that's because it's how Ted likes to remember his friend: a guy who took the maximum of his short life. Ted always talk about Barney as if the kids didn't know him.
In "Last cigarette ever" episode, the kids do not seen to be surprised to discover that their uncle Barney used to smoke, as if they didn't know him well enough to be surprised about this.
Doing the math backwards, Ted's daughter seems to be 15 at most, and the story is told in 2030, so she must have been born in 2015, which is 3 years from now (and yeah, this assumption I made was confirmed in season 7, she is/will be born in 2015. I formulated this before that). Since Barney smoked until 2017, he lived until she was at least 2.
Remember Barney married Robin at the end of season 7? Why is it that in the drawing the kids made of "aunt Robin" taking them to the zoo, or the beach does not picture "uncle Barney" with them?
Nobody knows what's Barney's job. Probably Ted does not tell this because he does not remember, not because Barney never told anyone. And now that he's dead, he cannot ask him, and if you think Ted will spare no details on his story, it's reasonable to believe he would ask if he could.
Barney Stinson is, of course, bigger than life. He has many more positive than negative points. That's usually how people like to remember their loved ones who passed away.
Ok, now it's public! In the next 2 years I can prove I said these words, and may or may not enjoy the pleasure of saying "I knew it!" :)