Keep in mind the key points here. The first key issue is that you are referring to a PPA. The second key issue is you are referring to Drivers.
With regards to drivers and hardware, the stability of drivers is going to be widely differing. This also applies to version
Your question explicitly states "When will the NVIDIA 364.19 package stabilize?" We can't answer that, and the stability of any drivers package can vary graphics card to graphics card. This also applies to version stabilization, since driver updates and fix packs require version bumps because of various reasons (ABI breakage, etc.; case in point how the kernel updates happen too).
When we add into account that this is a proprietary PPA, we cannot answer the question as we do not maintain the PPA, and we cannot guarantee that any users will be related to the PPA and be able to comment (this is usually the case: most PPA maintainers/groups are NOT on Ask Ubuntu). Therefore, we must vote to close it as unanswerable within the scope of the site within the confines of the available close reasons (though there is no strict rigidity to these reasons, there is some level of rigidity that must be adhered to)
The current close reasons as of today are (I just copy-pasted the close vote window is all, don't yell at me for incompleteness on things):
- duplicate of...
- This question has been asked before and already has
an answer.
- off-topic because... (some reason)
- This question does not appear to be about Ubuntu within the scope defined in the help center.
- unclear what you're asking.
- Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s
hard to tell exactly what you're asking. See the How to Ask page for
help clarifying this question.
- too broad.
- There are either too many possible answers, or good answers would be too long for this format. Please add details to narrow the
answer set or to isolate an issue that can be answered in a few
paragraphs.
- primarily opinion-based
- Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost
entirely based on opinions, rather than facts, references, or specific
expertise.
The question is not a duplicate of any other one, so #1 is not an option. #2 is not an option because it is technically on topic as it is about an Ubuntu package/PPA. #3 is not valid because you are not unclear in your question.
That leaves #4 and #5. "Too Broad" could apply because the question is fairly broad - you ask "when will it be stable" and the answer ultimately becomes "Why is it not stable" with too many answers. This was one option. However, #5 is a better fit.
Close reason #5 is such that "Answers to this question will be based almost entirely on opinions." This fits.
As I stated above graphics drivers' stability will vary from graphics card to graphics card, and Ubuntu release to Ubuntu release. Therefore, someone may have a graphics card that works perfectly fine with the driver and is stable on 16.04, but you don't, or I don't, or anyone else doesn't. Because the stability of a graphics driver pacakge will vary wildly, answers regarding it (in many, but not all, cases) are opinion based. As well, nVidia doesn't visit here so there's no 'factual source' to rely on here. (You also see this in the Windows world - a driver isn't stable on all cards).
Also, you state in the question that this is in a PPA. PPAs are not officially supported even though many on this site recommend them in some cases. There is zero guarantee of PPA packages being stable (in actual usage OR in version consistency of a stable nature), which further drives the answers to all be opinion based as there's nobody who can report factually on the stability of packages on that PPA, and/or there's still no way to state the stability of a driver on any given hardware, as above.
The third part is, we are not obligated to do your research for you - if the update policy is documented somewhere, then it would have been posted on the PPA, or the team that runs it. If it is not, then we are not obligated to do the research to try and find it where documentation would not exist.
That's my analysis, and why I think your question was closed correctly as "Primarily Opinion Based".