I think Tuhopuu was just a testing branch of Blender.
Developers used it to make radical changes to the program. Sometimes if the changes were useful they were incorporated into the program. Supposedly much of the current version of Blender came from Tuhopuu but that is just hearsay... you would have to see the developer logs to know if that is true. AFAIK tuhopuu has been inactive for over three years. I don't think it has anything to do with the supposed upcoming reworking of the UI.