It's a very NICHE market but it does make sense for some?... the example they showed before was an EXCEL spreadsheet.
So it can be carried like a really thick phablet/tablet but open to give double the screen size or show two different programs side-by-side.
Still, if you really need the portability I think a small phone/tablet is what people would do and if they absolutely needed more screen space due to WORK I think people would go with a small laptop or larger tablet.
INPUT is the problem so I'm not clear on who the target market is:
1) needs extreme portability, and
2) needs larger screen, and
3) touch/stylus input is sufficient