The future is Solid State...
I can't help thinking the longer term future is in solid state memory. Even a current generation Flash chip (inside its plastic body) is much smaller than the surface area of a CD etc. so even if we use the same surface area of flash chips as a CD has in area, then Flash gives a lot of storage space even now, so give it another 10 years and it'll be a lot higher. Also once chips become 3D (with many 2D chip layers sandwiched together), then its going to have vastly more storage. Also as its a memory chip it'll work even now in 3D, as its only going to be accessing one layer at a time, so power usage isn't going to be a problem.
So within a decade we are likely to have very high density solid state memory (regardless of if its Flash, Phase Change memory, or Memristor based memory or whatever). Its very likely to be into many Terabytes of storage sizes. With storage this big, it'll be easy to even create redundancy within the chips themselves for customers who wish to configure their storage in this way. Also the chip would only need to be powered up say once every year to then check that all its copies were the same. Each chip would then operate like its own RAID array and then for customers who need very good safe storage, they could create RAID arrays of these RAID array chips to create each drive (then RAID arrays of the drives if they really wish ... if they are really paranoid they could then create RAID arrays of entire data centers (so RAID ^ 4 for the ultimate in paranoid storage)). It won't matter if its using 4, 8 or even 16 copies of all the data as it'll still be smaller and faster storage than physical disk based memory and much easier to access. So I don't think Holographic storage will ever have a chance of growing into a viable business.
No solution is perfect, so we will alway need redundancy within redundancy etc.. in some form, but I still can't help thinking future solid state memory (in say a decade or less from now) is going to totally wipe out all long term backup storage including any chance Holographic storage will ever succeed.