All of the east side of Highway 27 on either side of Rexdale Blvd are strip malls, and there is Woodbine Mall north of this development. This is not an area that is starved for retail space.
A walk from the non-existent GO Train station for Woodbine (the one coming in 2030) to the casino would take an hour, according to Google Maps (I think you could do it in under forty minutes). This is not a walkable area. If they build the Woodbine GO station, they need to have a tram or something to get people to the casino.
The Finch West LRT is not finished yet, and no plans or funding have been procured to extend it to Woodbine. Even if it was extended, the current projections are that it would carry about 2,500 people a day. Not much.
Do people who are at a casino want to leave the casino - and walk outside! - for ho-hum retail?
There's a possibility that I'm wrong here, but this development has always felt very boondoggle for me. For it to work, the grounds and the area around the casino would have to become a destination. The current architecture and plans suggests that is not the case. It seems like what it is: one of Dougie's buddies wanted to build something in Rexdale, and Dougie said yes.
(I also find all casino developments kind of gross because they are built on capitalizing on other people's misery.)