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The Smoot paper is, it seems to me, quite similar to what I propose, except they do not seem to squarely face the fact that the hologram screen is in our future - it is obviously not in our past.

Assuming for the sake of argument that our future event horizon is the Wheeler-Feynman perfect absorber as Hoyle & Narlikar imply - then very simply using the retrocausal principle combined with Igor Novikov's consistent Feynman history loops in time
dark energy density in our past light cone = (c^4/8piG)(area of our future horizon)^-1
Maximal entropy of our observable universe patch is the asymptotic constant area 10^123 BITs of our future horizon.
Arrow of time is trivial because the initial area of our future horizon hologram screen was precisely 1 BIT, i.e. dark energy density hc/Lp^4 
General formula is  hc/N(t)Lp^4 where 
area of future horizon at cosmic time "t" is N(t)Lp^2
Therefore, it really is 
From Eternity to Here 
in a much deeper sense than Sean Carroll intended in his new book.