Without VR entered into the picture I agree with much of the sentiment of this thread. The idea of iterative console releases just feels wrong to me; if it means just better performance, graphics or whatever on a regular screen.
But with VR entering the picture my view point is a bit different. My suspicion is the PSVR, and VR in general, while workable with the current PS4, just requires some extra muscle to really get it where they want it. If they want to release an upgraded PS4 so VR can be more immersive, fully featured, etc., I'm all for it. I don't really want a gaming PC (basically the same or similar situation) so a PS4K that pushes a higher quality VR experience is welcome in my book. The 4K part is just a bonus IMO.
Aside from that I feel like an iterative console structure could work or it could tank. It's all in the details, delivery, timing, price, and software; all have to be just right and there are way too many unanswered questions.
Will the new system offer a substantial increase and enticing enough price to warrant purchase?
Will future software be created across the PS4 branded devices so prior PS4s are supported adequately and new versions of software not gimped by old hardware?
Will PS4s continue to be made and supported or dropped in favor of the new model?
Will Sony try to iterate too often (like every year or two) or just enough (like say every 4 years)?
Will they message and market this new business model to customers well?
etc.etc.etc.