Hi StarLite,
I am not with Laminar Research; just a flight simmer.
My original purchase of X-Plane was version 10.25 and software upgrades were made available when released from Beta versions. The software had an option to download the Beta version so those flight simmer who knew what they were doing with X-Plane could download these beta versions as well to assist Laminar Research to sort out bugs before that update version was officially released. The last official update release for XP10 was version 10.51
At that same time XP 10.51 was released, X-Plane 11 was being continually released for some time in Beta releases. XP11 is a totally different package to XP10 which was the reasoning for the long beta release transition. They cannot be mixed in any way. One will corrupt the other.
With the dramatic change in software development, to acquire XP11 you had to or you have to purchase the product as you do in the same manner when you purchase a different brand of car from and old beetle volkswagon to a jaguar.
So, at the moment, the official release version, to the best of my knowledge, is version 11.20 but there are more advanced Beta versions for those who know what they are "doing". When you start the software there is an option to check for any updates. If there are any you will advised with a message and XP11 will automatically download that update. Again if you are just a "flight simmer" then I would suggest you don't tick the box to download the Beta version as an alternative. Also, unless you are into or want to get involved with Virtual Reality, version 11.20 and above also has the option to download that version/option as well. Otherwise, don't select the option. Run with the conventional version
So, in answering your question.
You are about the 3rd person asking about X-Plane 12 in this forum. The official answers I have seen in this forum from Laminar Research staff is that they are too concentrated and busy on getting version 11 completed and improved with updates (currently 11.25 with a Beta release) with no knowledge of or planning an X-Plane 12 version. If and when a version 12 is released that is an unknown even with Laminar Research staff.
There are two issues that I see:-
1. Any XP11 official release versions that become available up to 11.99 (?) you will be able to download to upgrade in the same manner as you could with XP10 at no additional cost; and
2. If a XP12 version does become available then I would expect you will have to purchase that new version as it will be a dramatic change in format just like the change fro XP10 to XP11.
Good luck and welcome to X-Plane.
Glenn