HI @Ollesson ,
Since IIS is shipped with the Windows Server operating system, I personally don't believe it is going anywhere, as for major updates they seem only to come whenever a bigger release of Windows Server is released.
Security is however important, so I believe when new vulnerabilities are found in IIS, these will be fixed as soon as possible.
For now there haven't been any official announcements about the future of IIS 10 or any upcoming releases, the only news available are found here:
https://learn.microsoft.com/en-us/iis/get-started/whats-new-in-iis-10-version-1709/new-features-introduced-in-iis-10-1709
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Best regards,
Leon