I find that the shift from something as core to an IT department such as a RDBMS or OS takes a long time. In general there appears to be the following steps followed:

1) Evaluate alternatives

2) Prototype use of selected alternative(s)

3) Pilot project using selected alternative

4) Pilot system migration to new standard

5) Overtime migrate rest of the systems to the new standard

This often takes over a decade and can be dropped at any stage due to change in management, key technical staff or even the industry.