Wake’s library system seems to be intentionally more decentralized than many, with more resources going into building and stocking the outlying “regional” libraries than many places that have dazzling central branches. It makes sense, I guess, because Wake is an enormous county - and what’s more, the approach seems to be successful: Wake has about 10% of the state’s population, but its libraries account for over 25% of all circulation of print materials in the state.
That said, the popularity of the county’s library system (and how crowded they can sometimes be!) does indicate there is demand for more. In recent years, they have been adding new libraries, and upgrading existing ones from “Community” to “Regional” - so while I would not expect them to build an Architectural Marvel™ of a new library downtown, it certainly would make sense for them to upgrade/replace the existing “express” library on Fayetteville Street with something bigger and better, as the population in the area around downtown continues to grow.
The county is certainly willing to work with municipalities as far as where to locate libraries and what they will look like (See: the new libraries in Cary and Morrisville) so a good opportunity I see would be as a ground-floor occupant of one of the buildings in Raleigh’s new municipal campus across Hargett from Nash Square.