The article says that this new type of engine (VASIMIR) would probably need a nuclear power source.
In fact, whenever you want humans to go out far from Earth, or stay for a long time, nuclear is the only feasible solution to power needs - providing enough power per pound.
They have some prepared some great options already, like the low-power DUFF prototype, only one foot at its widest: http://ansnuclearcafe.org/2012/11/30/matinee-duff-space-reactor/
Russians have been putting up 10 KW reactors (TOPAZ) for decades. Wikipedia says (http://en.wikipedia.org/wiki/Nuclear_power_in_space): “In 2020, Roscosmos (the Russian Federal Space Agency) plans to launch a spacecraft utilizing nuclear-powered propulsion systems, which includes a small gas-cooled fission reactor with 1 MWe.”
A small reactor could provide high power to a habitat for ten years without refueling.
The bottom line is that nuclear reactors with plasma engines can really open up space for commercial activities and settlement, without any big technical breakthroughs needed - just the investment and government approval for the nukes.
In ten years, it could be possible to have a base on the Moon, out in cis-lunar space, and on Mars with plenty of power and a bunch of robots working away, if it was a high priority, and in twenty years if it a second tier effort, where Government just assists commercial ventures. After that, it is off to the races.
They've got the best record when it comes to nuclear power safety.