The beginning of the end of Remote Mailslots as part of Windows Insider

You cannot push work on people, especially if they don't necessarily control the app(s) depending on the features being removed. For all I know, Mailslots may be critical to some apps that have been working perfectly fine for decades but whose sources were lost or can no longer be built, or the risks/benefits ratio (high risks and zero benefits - to be clear) cannot justify modifying them today. These apps will stop functioning, and the users may either see this as an opportunity to move to another platform (fool me once...) or stick forever to a version of Windows that works for them, which, in both cases, are losses for Microsoft and a huge burden for the users. Don't confuse changes that benefit users with changes that only benefit you.