I could really see Mandarin take off if they would adopt a writing system similar to Vietnamese.
Numbers are a great example of that. We all have our own words for numbers, but can all communicate it with its associated symbols (which are different in arabic script for instance, though everyone's agreed on european script).
Mathematics is full of those symbols we communicate with regardless of their pronunciation in different languages, e.g. the 'for all' and 'there exist' symbols for instance, but also the equal sign and the integral, set notation etc etc. They're all concept, ideas, and have associated symbols.
So why wouldn't we all use chinese 'synbols' for our 'everyday' vocabulary when we write. It's be harder to learn to read 1 language, but so much easier to learn to read all of them.
When we communicate in western languages an idea I from person A to person B; then when A translate I into a translation t in a language l that both A and B understand. then B translates back t into I'. It's actually pretty hard to get I' to equal I. Where as with chinese characters, my understanding is their characters are closer to the ideas themselves. Potentially making it easier to communicate between each other across multiple languages.
Chinese script is logographic: each character roughly refers to a single morpheme. There is also a degree of phonetic component to the script (to some degree, it's a game of playing "what sounds like fish and has to do with food?") But morphemes are not universal across different languages, and phonetic games can quickly become obtuse: Japanese kanji is basically completely unintelligible to Chinese speakers, despite literally deriving from Chinese.
Even within the different Chinese topolects, the actual comprehensibility of the standard writing system without having been specifically taught it is I believe only in the region of trying to understand Spanish knowing only French.
But it's obviously not necessary, because all writing still has just as much context as speech does. The fact that you need the context less doesn't somehow make it go away.
However, if I were Chinese, I might worry that due to simplicity, the phonetically-written Chinese would eclipse the traditionally-written Chinese quickly. Those sentences which only make sense in traditionally-written, not spoken or phonetically-written Chinese, would obviously be a huge cultural loss. Not everything is about making business more efficient.
You might be interested in this:
http://www.zompist.com/yingzi/yingzi.htm
One interesting thing I learned from it the logographic aspects of written Chinese have influenced spoken Chinese by encouraging short, phonetically-ambiguous abbreviations that tend to replace the original phonetically-distinct words.
> Those sentences which only make sense in traditionally-written, not spoken or phonetically-written Chinese, would obviously be a huge cultural loss.
That's already happened to a degree. The Chinese dropped written Classical Chinese for written Mandarin, which is based on a vernacular. That's akin to the West dropping written Latin in favor of vernacular writing. I understand Classical Chinese needs to be translated to be understood.
They could also easily introduce a second, easier, writing system, and maintain a low-high kind of language (like many countries do). Eventually the second easier one will tend to dominate, but even until then, it will be easier for foreigners to learn it, and for chinese to learn both.