i don't think it's making a comeback just yet.

many companies have tried and failed, but when someone gets it right, it will take off.

i think.

i'm so over giant bricks and i'm waiting for something small and big (and half decent) at the same time. 

It actually looks pretty good...  I still have my original razr somewhere.  Interest piqued.   EDIT: until I saw the RRP :D

In my experience "the next big thing" is usually something everyone desperately wants from day one of it being announced.  Foldables are too niche to be the next big thing.  They might be the next iterative thing that evolves into other technology (a new e-reading / art / interior design experience for example), but I just think they're a curiosity for the next 5 years at least.