This thread is pretty amusing with all the wrong info running around.

Dust was never developed in carbon. That trailer isn't done in carbon either, it well predates the first demos of carbon by nearly two years. IIRC at that same exact fanfest we saw that trailer we got to watch the devs play through their first barely alpha build and boy was it ugly made minecraft look like it was running on crytek. Dust has always been running off an unreal engine, in fact they got into a little squabble because they had started dev before actually licensing it. As a side now a dev now long gone once mentioned that Dust development had been taking longer than expected because all the art was being done first for unreal 4 then down scaled for unreal 3, even if true its likely that this practice has been scrapped in order to try to rectify how far off the dust dev time table has been pushed.

Anyways, Carbon showed up a few years later making its debut for the new character creator in eve and then Captain's Quarters, which was really a dry run since it was at the time planned to have World of Darkness running the carbon engine. Carbon can do some really neat character model rendering, the tech demos they gave at Fanfest were pretty damn impressive. Unfortunately, carbon is a giant resource hog, computers were dying right and left just running the tiny captain's quarters. With the Incarna debacle halting all resources in walking in stations (thus carbon development) carbon was largely scrapped. The final blow was when they quietly announced that WoD had scrapped all their carbon work and dropped the engine.

In summary Dust was never meant for Carbon and Carbon is dead, no resources at all are being devoted in fixing its problems and it will largely only exist as the current Eve character creator and tiny pointless room, any future walking in stations tech will likely never use it assuming the eve population ever lets them explore that area again.

Speculation: Any revisit to eve walking in stations would likely involve scrapping all Carbon related assets as using which ever Unreal engine that Dust is currently using to allow better interfacing walking around stations. (having 2 engines interacting in the same space would be a nightmare)