Metro North/Dublin Metro: I always thought terminating at Stephen's Green was a short sighted plan, so extending South makes sense. I assume it can't be taking over the Green line, as if it was, the destination would be Cherrywood or even Brey. However Sandyford seems an odd destination, as it's hard to see a route that doesn't shadow the Green line. I would have thought Harold's Cross, Terenure and out towards Firhouse and Tallaght would have been a sensible option.
DART Expansion: I see mention of Drogheda and Maynooth, but no mention of the Kildare line.
DART Underground: No mention that I've seen. I saw some options for a "cut price interconnector", including a tunnel from Heuston terminating under Pearse, which would seem to miss the point to me.
Electrification of Belfast/Cork/Limerick: I certainly think this should be in a 23 year infrastructure plan, and I would see it as essential for meeting our climate change commitments, but I very much doubt we'll see anything with so much foresight.