Shown in what? Movies and series? In those holograms and transparent screens are used because it allows the audience to see what's happening, trading realism for improved visual story telling.
As for realistic where mobile tech is going, my guess it will be pretty much what we have now, just more compact and foldable.
Eventually advances in AR and brain interfaces might make the "rectangular slabs" be replaced by something more discrete which no longer requires physical inputs. Doubt they'd be called a mobile phone though.
Also checkout Heroic Launcher, Epic gives free games every week, there's plenty of fun to have with those too.