Hello,
I'm so excited for the future! Glad you are back. I'm still using FSX and loving it but definitely ready for an upgrade! I look forward to 2020! Happy programming! Here is my list:
Backwards compatibility with plug and play devices (some are outdated but still work)
Networking capabilities for external displays and gauges within the program (No need to use WideView or 3rd party programs), this would be useful to home cockpit builders with more than 2 external displays
Built in interactive live traffic which includes airport ops, ground ops, gates, hangars. etc.
Built in liveries of real world aircraft
I agree with much that has been already listed. Thank you for the opportunity to give input!