The basic premise may be disruptive in a "Big Bang" move but could be accomplished gradually by building new facilities and shifting project flow over time.
Also, the DoD makes fast changes like this all the time as the result of BRAC. Government employees don't tend to just up and change jobs - they are career workers who like the stability and promise of a pension.
How is this different from Wallaby Card? Is this a live product? My understanding is that the networks were not allowing such products. For example, Google and PayPal both planned to issue dynamic "wallet cards" but were blocked by V/MC.
Also, the DoD makes fast changes like this all the time as the result of BRAC. Government employees don't tend to just up and change jobs - they are career workers who like the stability and promise of a pension.