Are you trying for just a low ABV or are you looking to make a NA beer? If you are going for NA, holding the beer just above the ethanol boiling point would drive off the majority of the alcohol, leaving you with a beer with little alcohol remaining. This doesn't get around the cooking part however. As AJ said, low pressure would allow for alcohol removal without needing to increase the temp as much, but that will also change your eth vaporization point.
It's really a purely theoretical question; I'm not planning on actually doing this and I'm not really even focused on whether or not it would work (I'm certain enough that it would work.("It" being the evaporation of the ethanol.). -I'm really interested in how you could calculate/ test the ABV before/after or the ABV difference.
I'm also curious just how long it would take to boil off the majority of the ethanol.
--If you're only brining the beer up to 78C (172.4F) and only need to do it for a couple of minutes the darkening of the beer would be minimal (i'd have to carb it all over again, though). --And if the time it takes to boil off x% ABV is unknown, and I have a way to measure before/after ABV I could figure out this one, so the two questions ARE sort of related.