I feel flattered to be called reasonable. Many will disagree with that qualification of my character
Anyway, we built all our apps Cloud first and port them to Server/DC as soon as they start gaining traction. We can do that with relative ease because our Cloud and Server apps share ~95% of the code base.
However, we made some significant investments to achieve this. In short, all business logic is on the front-end. The back-end only consists of an API for basic CRUD (with authentication). There is no logic involved. The front-end is based on IoC principle with dependency injection. This allows us to create abstract logic for most operations and inject detailed implementations for each platform.
If you’re serious for long-term support of both Cloud and Server/DC, I think this is a worthwhile investment.