The Systems Architect: the realistic visionary or the visionary realist?

Systems Architects lay the foundation for systems that are likely to be put into use in the near or distant future. The systems' context may have changed by then. Also, putting a system into a context changes that context in sometimes unforeseen ways. A visionary attitude is therefore necessary for the systems engineer/architect. 
On the other hand, making a system architecture implies committing to it. The architecture thus has to be realized in the given development timeframe. It is therefore paramount that the architect knows what can be realistically achieved in that timeframe, also considering technological changes.

The systems architect thus has to hop between a realistic attitude and a visionary attitude. This is the central theme of the key note.