There are a lot of misconceptions when it comes to cloud based storage. Many people seem to think that if they upload something to the cloud, it will be there forever, ready to be accessed and shared at any time.
The reality is however that the cloud is just the same as any other storage. The cloud is just hard drives owned by someone else, and your files are accessible as long as they stay in business.
In addition to this, your files are only accessible as long as the format that they are saved in are still relevant and being used by software.
Technology tends to move fast and leave the previous breakthroughs behind as it advances and becomes better and more efficient. For data storage, this means that as new formats become more widespread, the older formats of previous years start to become obsolete.
The software that is compatible with these formats also start to become obsolete, and the future is heading towards a more open and shared way of storing information. An example is proprietary formats such as WMA files, that are only compatible with the Windows Media Player software.
10 years ago, people would buy a windows PC, upload their music files into windows media player and they could then enjoy them when they liked. Nowadays, hardly anyone uses this format, as it relies on the proprietary software to use the file. Formats are moving towards a shared type that anyone can use without having to have one specific piece of software.
Of course there are ways you can convert your files into the latest format using data conversion tools, and this can keep you files safe at least for a while. But since new formats will always come out and be adopted, you will end up having to keep updating you files in order to keep them safe in the cloud.