There are a few things that were never quite clear. On askubuntu we can ask questions about third-party software, package installation and hardware issues. Can we also ask about software compatibility like
"THIS_PACKAGE was installable in 14.10, why doesn't it work in 16.10 and when will we be able to install it?"
Sorry if this question is basic, this concept was just never clear to me.
I don't think I quite agree with Jacob, but I think that's mostly because the question you're asking can be viewed in a few separate ways. You're actually asking three separate things:
Third party software and compatibility, installation, usage are all on-topic here. Yes, there will be times when "asking somebody else directly" might be better. We might not have somebody familiar with the software or that combination of software and Ubuntu setup, or hardware, etc, etc. But we might.
Speculative questions about development releases are off-topic. Not all questions about upcoming releases are but "Will +1 support y?" is the sort of thing where neither we or the app developer really know until it's release time.
I'm sure there are exceptions people could point out but the test is whether or not it can be answered and still be relevant (and accurate) by release time.
Speculative questions about third party software are off-topic. This is really just an extension of #2 and we probably don't have a single specific close reason about this but only the developer(s) knows their plans for the future. That should be obvious.
So a question about third party software (even current compatibility) is fine in my books. A question asking about the future support of it on a future version of Ubuntu isn't on at least two counts.
That kind of questions should be asked to the developers directly. This is in general not the kind of questions that should be asked on AU, simply because it is unanswerable.
Asking developers directly is also more useful; as an example: it happened someone asked me on Launchpad if and when an application would be available for the current Ubuntu version. I simply forgot to copy the package's ppa. I would probably not have noticed when asked as a general question on AU.
man <application>), where should be described how to file bugs etc. Also the HELP section, if it exists, should include the developer's coordinates. Many applications are hosted on Launchpad: launchpad.net