If 3d Xpoint is cheaper, lower latency, and higher throughput than DRAM, yes, it will obsolete DRAM. Currently it is higher latency, and lower throughput. And it is cheaper on a per-GB basis, but with a much higher minimum GB (like, 128GB).
I don't think that it's intended to replace DRAM. It's going to be cheaper than DRAM (price-wise, I expect DRAM / 3DXpoint ≈ 3DXpoint / NAND), but significantly higher latency (the article says an order of magnitude, but those figures don't seem to include bus stuff etc, so it might be a bit more. Total latency will likely be in the range of a few hundred nanoseconds). That, and the limited durability (much higher than NAND, but still limited).
I think this is going to be amazing for "in-memory" data bases: it's cheaper, still very fast, has higher capacity and is persistent (the article doesn't even mention that). But it won't replace DRAM any time soon imho.
Even if it just cheaper and same order of magnitude latency, it'll likely take over. High end systems would still have DRAM as a large L4/LLC cache, while low end ones will omit it.
