Highly doubt they'll transform Habbo into 3D. Even if they change their GUI, it's all a mere fact that they want to look more mature instead of staying with the kiddish UI.
Habbo will absolutely never go 3D: FACT. Currently, Players are getting smart enough to realize that Habbo is just a big waste of time. In 2008, Habbo had more players on the US hotel than they do on the UK/US Merged Hotel. Why? Retros. They are finally realizing that as much furni and coins as you want, whenever you want, is worth the risk of Sulake maybe possibly sometime in the possible indefinite future criminally prosecuting you.
Habbo's user count atm:
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Currently there is about 2500 people in the top 25 retros.
Therefore, since Sulake is constantly losing Habbos to retros, they will never take such a large risk.
I've always wanted Habbo to go 3D but the video is nothing like I thought. I would like Habbo to keep the graphics but be able to change what you are seeing. If you don't get what I'm saying, I've made a very shitty diagram. It would take longer to design furni but it would be so much easier for room/casino builders like me.