Re: How I Met Your Mother: Barney and... (Spoilers ahead...)
We've seen the mother's foot in the apartment of the girl Ted dated for awhile. It was her roommate. So unless Robin was living with a roommate and they never put two and two together... No Dice.
It will NEVER be Robin.
Despite what Marshall did in saying "Not Yet" to Lily.
They could go a different Route and have the mother be named "ROBIN" too I guess.
"You fool! You've fallen victim to one of the classic blunders! The most famous of which is "Never get involved in a land war in Asia", but only slightly less well known is this - "Never go in against a Sicilian, when death is on the line!"