Absolutely, yes, NVMe drives will hit price and capacity parity with current SATA drives at which point SATA will fade away. This will probably happen sooner than people think, within a few years.My question is a bit of a two parter. Will we see NVMe drives eventually reach price parity with current SATA/AHCI drives? Does the increasing capacity of SSDs make power loss protection any more important?
In a pure technical sense, as the capacity of an SSD increases so does the size of the mapping table so it's logical to think power loss protection becomes more important. There are two approaches to handling unexpected power loss: increasing the hold up time the drive has to clean up and safely shut down by adding capacitors, or improving the robustness of the firmware and decreasing the amount of work that needs to be done during this additional hold up time, reducing the amount of additional capacitance required. I unfortunately can't go into too much technical detail here as this strays into special sauce territory, but think of similar work and techniques done on the filesystem level like journaling, write verification, and increasingly sophisticated error correction. We tackle the problem from both ends, so the presence, or lack thereof, or large power loss protection capacitors are not necessarily indicative of how robust a drive manages unexpected power loss. In fact, if you check your SMART data you're likely to see some amount of unexpected power losses recorded you didn't even notice.
Funnily enough, the trend in the datacenter space is not build in any additional power loss protection on the drive level, but to push the cost down as much as possible and build in redundancy at higher levels. Relevant xkcd: https://xkcd.com/1737/