Is Our Universe Likely to Decay within 20 Billion Years?
  Observations that we are highly unlikely to be vacuum fluctuations suggest that our universe is decaying at a rate faster than the asymptotic volume growth rate, in order that there not be too many observers produced by vacuum fluctuations to make our observations highly atypical. An asymptotic linear e-folding time of roughly 16 Gyr (deduced from current measurements of cosmic acceleration) would then imply that our universe is more likely than not to decay within a time that is less than 19 Gyr in the future. 
Don N. Page