I am totally in favour of safe standing areas as a logical extension of the singing area we promote (not much of that lately though but that is due to other matters).
It works well in Europe - Germany in particular - so there is no reason other than the intransigence of those in power for it not to be put in place on a sensibly controlled basis, i.e. not the whole ground but areas where it will be appreciated.
However, the Chief Executive of the Premier League, Richard Scudamore, is vigorously opposed to it and is unlikely to back down as he has stated his position on many occasions.
Nevertheless, the only reason it cannot be implemented (other than government approval) is that the Football league hasn't actively promoted it. Get them on board and it could be done.
Sides getting promoted to the Prem might have problems subsequently but if the same systems can have seats locked down then the area reverts to full seating anyway. Also, from what I see areas of many grounds, Prem or otherwise, chose to stand so would there really be little difference other than acknowledging and formalising the issue?