SCOS firmware releases?

This probably won't be much help, but outside of NDA, all you can reasonably assume is that there will be periodic updates to the current supported code platforms. I'm not really sure if there is a way to find out in advance when the next 7.2.x or 7.3.x update will be out. I typically find out about them after the fact by reading release notes. Google search for something like "Dell SC release notes". Also, sometimes certain versions are not made available to all customers, and remain under something called, "Directed Availability", where I believe you have to be experiencing one of the issues resolved in that version to upgrade. For example, 7.2.51 is out, but 7.2.40 is the GA version right now. (or at least last time I called into co-pilot).

As SCOS versions become the recommended version to use this site is updated:

SC Storage Customer Notification: Targeted Storage Center OS Version By System Type
https://www.dell.com/support/article/us/en/19/sln308479/sc-storage-customer-notification-targeted-storage-center-os-version-by-system-type?lang=en

Another option is to follow How to Subscribe to receive Dell Driver and Firmware Update notifications
https://www.dell.com/support/article/us/en/19/sln156799/how-to-subscribe-to-receive-dell-driver-and-firmware-update-notifications?lang=en