Battery and motor tech has progressed massively in the last 10 years, the projections on energy vs weight for electric propulsion is through the roof at the moment. This is why there are now many projects developing electric vehicles from trucks and busses to planes and ships. Its only a matter of time before there is a major breakthrough in energy storage that will significantly affect this area. I think it's fairly smart to get in on it in any way. The big issue is that this tech has the ability to completely change transportation especially air travel, as having a large bus sized quad-copter is probably where this will go, not necessarily fixed wing aircraft, except for long range. Rex is probably smart to retrofit the SAABs for another 20-30 years of service life until that next step arrives, rather than buy into super expensive step change vehicles in the interim.