Bit by bit the whole land is being re-themed to better match the Tron-esque motiff by 2021. We've already seen this with the red rocks turning shiny blue, the purple wall makeover, and the wall along Monster's Inc. Now some of the more elaborate intergalactic structures are being taken down and will likely be replaced with more dark and natural sci-fi elements.
By the time Tron opens, they're hoping to have a more cohesive (looking) Tomorrowland.
EDIT: In other words, expect a lot of blue and silver.