Well… the migration tool was publicly promised “by the end of the year (2015)”, so…
Oh… I just read more recent tweets by SmartThings and Hawkinson. Apparently “end of the year” is now just a “goal” and then a “hope”. Big surprise. 
In case it’s not obvious, my point is that anything SmartThings says is subject to change at any time. That means any promises to keep Hub V1 supported are not promises.