I think part of the challenge with 2NC is having St Marys on one side and the Ring Road on the other. Still St Mary's is doing well, and there's room for development up and down St Mary's street.
Remember too there is quite a bit of development (including a cluster of apartments) just a little down the road in Marysville. Otherwise I could see some apartments maybe eventually going up St Marys street. St Marys below 2NC seems to be shifting more and more to a commercial/office corridor, so I doubt we'll see many new apartment blocks there (at least not ones without a commercial first floor maybe)
I think if I were Smart Centres, I'd
start building #3 and #4 soon so they have more slots available. #5 and #6 seem to be more suited to restaurant pads so they would be custom builds if/when they ever happen, but #3 and #4 are multitenant buildings and probably good to start construction now so they can recruit tenants to fill them in.
Thinking of that area in general, the other end of 2NC (Cliffe Street) seems prime for development as well. Personally I feel like that Marysville area is due for another grocery store, but that particular corner is probably too close to St Mary's Market. Instead, I could see a minimall area anchored with a Pharmacy working well in that corner. Jean Coutu's is already at the bottom of Cliffe, but Lawtons or Shoppers Drug Mart (most likely SDM since Lawtons is over in Brookside) would probably work really well there.