Re: Now this IS interesting
That the battery would die in 2-3 years reflects none of my observations. My 2007 (original) iPhone lasted a full 7 years through 2014 before the battery started swelling. My 2009 iPhone 3GS is still my mother-in-laws phone, working fine in 2015 with its original battery. Certainly I haven't noticed in failures in newer ones. No reason why an Apple Watch wouldn't live for 7 years without changing the battery.
So keep in mind that while batteries *may* fail in shorter time than the ones I've observed - Apple does replace batteries of their old devices - unlike most of their competitors.