Since, as you said, 16.04 is LTS, that means that the
I don't understand the relevance of your comment. 16.04 supports Snaps, uses X by default, and will be around long enough that snaps will be available for people to download and use within its lifetime, right? If that statement is true, then there is a security risk.
By the time desktop applications start to be packaged in snappy form, Ubuntu will be using Mir as the display server instead of X.org.
Why do you believe this to be true? 16.04 doesn't use Mir and is an LTS, people will be using it for years, and it is not even guaranteed yet that 16.10 will use Mir by default.
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