Well that's true, but given Valve have tied the Black Mesa and Aperture Lab. histories together - both in Portal and in Ep:2 - it's a fair bet that what you'll find at least has a passing resemblance to the styling of Portals tech.
That said - how they'd go about combining Portal and Half Life as games is beyond me - Portal contained very strict specs on where you could and couldn't create portals, as well as a lack of other weaponry available to the player. Half Life on the other hand features are far more "natural" world with other weaponry also available. They'd have a very hard time allowing you to create portals in the Ep:2 or Ep:3 worlds.
