64-bit required for MAS starting Jan 2018

Targets macOS
1

http://appleinsider.com/articles/17/06/07/high-sierra-runs-on-all-sierra-capable-hardware-starts-process-to-kill-32-bit-apps

And starting Summer 2018 all updates to old apps will also need to be 64-bit.

2

See this discussion https://forum.xojo.com/41077-should-i-bother-with-32-bit-desktop-apps-these-days