A downtown shopping complex will not work in Raleigh. Fayetteville Street Mall proved this and with so many other options available without going downtown (Crabtree, Triangle Town Center, et al.). no one will bother.
What's needed to get people downtown first off is an easy transportation route into downtown i.e. the light rail.
Once people have an easy way to get downtown, and leave, they'll actually consider going, then you worry about giving them a reason to go (i.e. attractions). Plensa would have been a good start.
Raleigh seems to be banking on the new convention center to do this and make the Raleigh revitalization work. Indeed, the convention center is the cornerstone of the revitalization.
The hope is that the convention center gets people downtown which causes new businesses, restaurants, et al. to open up to take advantage of the new business potential and these new business attract even more people downtown and so on and so forth. It's a chain reaction.
But truth be told, at least in the near and semi-distant future, you can forget about downtown shopping complexes, arenas, etc. as being part of that. It's going to be things on a much smaller scale and scope for some time.