"If this de-coupling continues to gather momentum over here, many will have to re-evaluate their go-to market strategies." I read that as "Make sim only contracts a shed load more expensive".
Aside from what is mentioned in the article, I think people are wising up to the fact that:
1) Smart phones are largely a mature technology. A lot of the new features being trumpeted like Bixby or Face ID are features created out of a need to have a something for marketing to shout about.
2) Now they are mature, unless you obsessively need something new and shiny a one to two year old refurbished former flagship gives you pretty damn good bang for your buck. I currently have an S7 edge and will likely replace it with a second hand one when I eventually break it as it is a good phone and does what I need. My only issues are non removable battery and expensive screen repairs!
3) Mobile operators generally provide poor customer service. At least if you buy sim free or second they can't screw up your handset by failing to deliver it/filling it full of crapware etc