No. Though it would be nice, it would likely lead to decreased performance, or lower level of detail in order to keep a good performance. It'd be nice, but I don't think it'd be practical.
This. Basically, the cells are a way that the game keeps itself organized. What's going to take longer to search for the right thing, a filing cabinet or a room full of loose paper? The cell method allows for high detail and good performance.
Besides, almost all games have loading screens. In fact, I can't remember playing a game that didn't have some kind of break or loading screen from area to area without using the "res and de-res" method of chunking up the gameworld.