It's definitely not due to running out of ideas. I have a Galaxy Fold and love it. I owned it for about two months before my wife went out and bought one for herself. And everywhere I go people want to look at it and play with it - quite remarkable.

I haven't encountered any issues with apps not supporting the wider aspect ratio. It's one of those cases in which Android's up-front investment in more flexible software paid off. Android apps were harder to write up front because they had to support resizable layouts from the get go, but by the time stuff like foldables were introduced the software library was already ready for it all.