Definitely a few interesting details here! I would think from an industry perspective that the sub-20% sales from standard bike shops would be somewhat alarming, however if this is all 2016 data the sale balance has likely significantly tipped in the last 2 seasons. I'd say anecdotally that all of the ebikes I see now (and there are SO many more than when I got my first back in 2013), a majority are from the major makers at this point.
The biggest thing that makes me sad at this point is the excellent European brands that left or shrunk in the US market (BH most significantly, but it also seems Haibike, Bulls, Etc have also lost their place as the most frequently discussed brands). Either replaced by the lower end online shelf bikes (Radrover leading the pack here...and I'd better not hear about them being an established brand...they started on indiegogo just like many others!), or the likes of Spec, Trek, Giant.
Despite this boom, I fear that the industry is going to miss the point - if all they see is dollar signs today, tomorrow and next season - they are going to miss the opportunity to make a huge push for bikes as legitimate transport in the US - tackle infrastructure (or support the ORGs that do so), sell long term support, and grow the sport as an every day lifestyle choice. If those things get missed over the next 3-5 years, there will just be more bikes in garages and an even larger sales cliff on the back end.