[Asbo Zaprudder]

That paper points out that our measurements of the expansion of the universe are insufficiently detailed or precise to be able to distinguish between models of its future dynamic behaviour. It doesn't appear to state anything about the nature of dark energy (or vacuum energy), which essentially remains a fudge factor of unknown origin.

The problem lies in the fact that quantum field theory neglects gravity, see:

http://math.ucr.edu/home/baez/vacuum.html