Re: Yes. That sounds about right.
Unless there's some kind of niche, kind of like how RD-RAM was during the early 2000's before Rambus decided it was a great idea to sue everyone, you're pretty much correct. Samsung has a good reputation for quality with their SSDs, and are well positioned to exploit Intel's lack of clarity and expense involved with it if Z-SSD doesn't have the vendor lock in problem, can produce a lot of their Z-SSD devices at a low enough cost, and has the same robustness as their 3D NAND SSDs it won't take much to relegate XPoint to a niche.
I have a feeling XPoint is headed the same direction as Itanium, really useful for certain things but nowhere near the mainstream ubiquity of x86 (though admittedly most of it now is x86_64 which was originally AMD's design) that Intel is so desperate for a repeat performance of, for the corresponding megabucks.