Valve seems to have opened up use of the Portal IP for other developers. While Warner Bros Interactive has yet to confirm Portal being in Lego Dimensions, a Portal Pinball table has been confirmed for Zen Pinball 2.
Portal was listed as a Lego Dimensions expansion on Walmart, with packaging previewing a Chell figure. Again, these details have not been officially confirmed. However, they seem to be legit, as Warner Bros Interactive has already requested that the listings be pulled. The same source also hinted at the Simpsons, Scooby-Doo, Jurassic World, and Chima. (Side note: cover image is mockup of what Portal playset could look like.)
However, Zen Studios and Valve jointly confirmed the Portal Pinball table. The table will see you indirectly controlling Chell and Wheatley via your pinball skills, in the service of defeating GLaDOS and making your way back to the surface. There is multiball with ATLAS And P-Body functionality, and a hidden playfield to attack the turret factory.
Both Lego Dimensions and Zen Pinball 2 are multiplatform, so expect to be able to play them on the platform of your choice, including PC, Wii U, PlayStation 4, and Xbox One.