Thinking about it a bit, I think I'd have

1. defined traditional suffixes and abbreviations to mean powers of two, not ten, aligning with most existing usages, but...

2. deprecated their use, especially in formal settings...

3. defined new spelled-out vocabulary for both pow10 and pow2 units, e.g. in English "two megabytes" becomes "two binary megabytes" or "two decimal megabytes", and...

4. defined new unambiguous abbreviations for both decimal and binary units, e.g. "5MB" (traditional) becomes "5bMB" (simplified, binary) or "5dMB" (simplified, decimal)

This way, most people most of the time could keep using the traditional units and be understood just fine, but in formal contexts in which precision is paramount, you'd have a standard way of spelling out exactly what you meant.

I'd have gone one step further too and stipulate that truth in advertising would require storage makers to use "5dMB" or "5 decimal megabytes" or whatever in advertising and specifications if that's what they meant. No cheating using traditional units.

(We could also split bits versus bytes using similar principles, e.g. "bi" vs "by".)

I mean consider UK, which still uses pounds, stone, and miles. In contexts where you'd use those units, writing "10KB" or "one megabyte" would be fine too.