Easily redeveloped, one stand at a time; the biggest issue would be loss of matchday revenue coupled with the building costs, but it could be done.
Start with the bullens and incorporate the Directors boxes, dressing rooms etc;
Main Stand next
Street End
The Park End could be left or the extra tier incorprated over time of the full development.
The other major issues will be planning permission due the to residential area; if The Old Lady was to be developed I wouldn't want it to loose to much of its character, would hate it to look St Marys, Stadium of Light, Pride Park and virtually every other new build stadium with no essence of a footballing stadium