While this looks all well and good, I have a couple problems, namely is the acceleration capable of penetrating armor plated steel ship hulls? If so, then this becomes a great weapon in close support of ships as the magazine can be removed an secondary explosions caused by direct hits could be a thing of the past.
If I'm reading the technology right, basically this is a very high powered catapult, meaning it's fire and forget, straight line trajectory so anti-aircraft and missile defense uses are neigh unto impossible as there would be no way to "direct" the round or have it home like radar, sonor, laser, video and fly by wire munitions.
As a ship to shore weapon, this thing would be devastating against soft (people) and semi soft (light vehicles, minimal armor and light wooden buildings) targets, but my concern is loss of velocity over extended distance. (Obviously they aren't going to release that data until they field it. ) Conventional weapons have given way to ship to shore missiles, so unless they could ensure minimal collateral damage, I don't see this being implemented, by 2020 or any other time.
Naval bombardment in support of a landing hasn't been a Navy tactic for many years, in part because we don't do conventional landings anymore. (though there are three tactical landing craft undergoing sea trials.) but their primary function is helicopter operations for troops and then logistical landings to disgorge vehicles, and materiel.
The military has had to contend with collateral damage reports over the last 40 years, in WWII carpet bombing and strategic bombing while effective also destroyed buildings and killed non-combatants. Something that if happened in a modern assault would be met with a media firestorm. Which isn't a bad thing, it's really cool when you can fire a missile from 25 miles away, fly in through a window and land on a bad guy's desk taking out the building which is oddly located next door to a school, a religious center and an emergency response center all of which didn't feel anything other than a slight tremor and a loud boom.