I think that if this is for real, that it would be hugely useful, even if it generates low thrust. Combine low thrust with a long term electrical supply (solar cells or thermopile) equals lots of delta v.
A satellite equipped with one might not need propellant and rockets to keep station. Probes could explore the solar sytem with significantly less propellant (used when high thrust is needed). With less need for propellant, the probes are either lighter or have more room for payload.
If this generates high thrust, all bets are off, everything changes. It would be kinda like the spacecars in Star Wars or the Jetsons (though they might need extension cords).
And of course, it seems that current explanations of the process are inadequate- so this may provide new insights into fundamental physics, leading to who knows what.
Or maybe it’s just cold fusion (and faster than light neutrinos, etc, etc) all over again. ( I have the same sense of excitement I had when I heard about cold fusion- I imagined nuclear power sock warmers!)