What scenario to adopt for saving/loading files in Cloud Computing era?

cloud computing is not actually new concept. We have had shared folder or shared documents for many years. So, I think "cloud computing" is more marketing propaganda than technical whatever.

However, what is good about cloud computing is that the provide, say Google, implemented replication of data transparently in the cloud. So, there are less chance that you lose the data. They say that it is more reliable than storing data on your own machine. However, still you will run into a situation that you need a copy on your machine and nowadays HDDs are cheap, although they, again Google, will say  it is better to save your valuable HDD space.

Then, we run into this question : How to present "Save" and "Load" document menu item under File menu? If on Chrome notebook, it should be either Web offline storage for disconnected mode and cloud storage for connected mode to choose, and if put Steve Jobs' touch on it, the "offline" document should look as the document file in the final destination, i.e. the cloud storage. By doing so, end-users can think saving and loading files just like current file saving/loading.
Under this situation, do current cloud framework support this transparently?

However, on desktop/notebook computers with local storage concept, it becomes a little more complicated : Should you provide two Open and Save ( Save As...) menu items each for cloud  and local HDD? Or is it better to save as a local file and triggers to save to cloud storage? When loading, which files should be presented?
You can choose "Only Cloud" and "Only Local" mode also for flexibility.
So, on traditional OSes, you can have these options to take ( any combination can be also considered ) :

1. Only Cloud / Only Local
2. Explicit selection either of the two
3. Save / Open a local file and that triggers accessing its version on cloud. So, the local file serves as a pipe.

How about the offline storage for traditional OSes? Should they be transformed to valid and official local file when necessary?

If the 3rd case is not considered, it is rather simple.
However, if Steve Jobs takes this problem into consideration, I'm pretty sure that he will think about the case 3, because if it can be done transparently, the user experience is the best.

Cloud computing makes things a little funny. Nowadays price of HDDs are really cheap, and huge. (OK. OSes became dinosaurs also, and they take lots of the space. ) If a S/W program is to be used for personal purpose, is it persuadable to use cloud based storage? (Well, yes, under some situation, but generally speaking, is it? ) Wouldn't it be better to use the good & old local HDDs?

Well, following trend is critical in this tech field. But since 2000, I've noticed that new trend was mostly about marketing and giving fresh feeling rather than solving problems a lot better way. Why I wanted to be a professor and researcher at labs was that I didn't need to be controlled by marketing oriented tech trend. However, I became an application programmer. Then it is easier to be controlled by that and even here in the U.S., I ran into many senior project leaders who just followed those trend without understanding what they really were and asked if I did something with those. If I didn't do anything with those, they tended to think I didn't know about it.

However seriously, we need to think about all this trend. I'm not saying that cloud computing is bad. It will be useful for some situation. However, when we adopt it, there should be clear reason to embrace it in our projects.