Well given a third of the site is going to the RCSI, it's unlikely the population will increase to any great extent, even with a higher density development...
The Irish Architectural Archive has the most fascinating collection of photographs of 'Old' York Street from the 1960s.
A lot were taken by the Dublin Corporation Dangerous Buildings Dept, some by Maurice Craig, and the majority not credited but clearly taken for archival purposes. Unfortunately from what I could make out, all of the pictures were of the northern terrace, i.e. the RSCI side rather than the 1940s terrace side.
It seems all the pictures were taken in anticipation of the northern terrace being demolished c1964, as appreciation of Georgian stock was much greater by then than the 1940s when the southern block was swept away.
The condition of some of the northern houses is truly shocking, but especially the notion that people were still living in these conditions in the 1960s in the very heart of the capital city. One dismal photo from 1962 showed a half landing with a magnificent timber window surround with fluted columns either side, and in front the most squalid conditions with a pail of water on the floor, a Belfast sink in the corner, what seemed to be some sort of wardrobe-like water closet squeezed onto the landing too, and of course all manner of filth and decay all about, with crumbling walls and plaster and the original arched window removed and a square sash put in its place.
Another picture shows what seems to be an entrance hall, with the arch that divides the reception hall from the inner hall half-bricked up with concrete blocks.
Outside the pictures taken by the Corpo were naturally of the worst parts, of barely-holding-together railing plinths and wonky railings, and other more significant structural issues.
Above all though, you could make out what a fine street it once was, maybe as much as 100 years previously. The houses semed to be in the majority c1750-60 in character - the doorcases in particular would remind you of Parnell Sqaure and other Gardiner schemes of the mid-18th century, with a lot of doorcases like this but maybe smaller and bulkier in scale:
Most interestingly though is that there were loads of doorcases as good as identical to those on the opposite side of the street today on these northern houses, the ones that seems to be of concrete:
There were more elaborate versions of the corbelled doors, but definitely not the exact ones - so they seem to have originated on the southern terrace where they are now. What's particularly sad to see is gothic timber panes in a few of the fanlights, and even in at least one of the half landing windows to the rear
Reading some bits and pieces from about the place it seems York St was one of the worst, if not the worst tenement area in Dublin in the 1940s, so it's no wonder the Corpo wanted rid of the southern terrace at least. In one house there were no less than 24 families living in its rooms - and all sharing a single toilet. No doubt conditions improved somewhat by the 1960s, though judging by the half landing pic you'd think otherwise...
There were new-fangled television aerials up on the chimneys anyway, so they had telly at least
It seems strange that the southern terrace was built to rehouse everyone c1950, yet it was another 12-14 years of utter squalor for the northern terrace before it was pulled down - why the delay?
Does anyone know of the RCSI bought the terrace from the Corpo and then demolish, or did the Corpo clear it themselves with the intention of rebuilding but never realised their plans?
Either way it's become much clearer as to why the Corpor rebuilt the southern block in a Georgian style - simply because the northern Georgian terrace was to remain standing and in use as tenements for many years to come, hence the character of the street was maintained. Indeed in one pic of the northern terrace, you can just see the brand spanking new southern block in the background
Hope to go back and try to find some material relating to the all-important southern terrace - it's due to disappear in a matter of days at this stage