Apple Watch - international roaming

Apple Watch Feedback

https://www.apple.com/feedback/watch.htm

NOTE: it will be difficult as the Apple Watch uses 2 different regional radios. A North American radio and a rest of the world radio. Even if roaming were possible, you could only roam in the region your radio was supported.

Nobody here knows what apple's business plans are,but as there are many different cellular radio frequencies in use around the world that doesn't seem likely.