Will Metric time ever be adopted by every country in the world?

No, the whole point of the metric system was to standardize units of measure intranationally and internationally. Time is almost entirely standardized as it is, so adopting meteric time makes extremely little sense. Also, the idea of 10 hours a day isn't the best because a tenth of a day is too long for most activities, so almost nothing that you do other than sleeping would encompass an entire deciday (working is really a collection of activities, and thus does not count). It would just be kind of an awkward unit on the day-to-day.