I'm sure this isn't a new idea, but here goes anyway:
I currently (and for 20 years) use Quicken Classic on a home-based Windows PC. I'd like my primary Quicken data file to be stored in the Cloud, so I could run full Quicken Classic from a Windows or Mac laptop when I am away from home. I would never run two simultaneous sessions, if I tried then just prohibit me from launching the new session.
I suppose I could do this today by loading a data backup file on a second instance of Quicken Classic, but then if I neglected to load the primary PC from backup when I return home, ugly data corruption would occur.
If implemented, this would be my all-time biggest Quicken enhancement.
Ken