Left Bank apparently isn't really chasing big loss leader anchors such as Neiman Marcus. They did prematurely leak that they were interested in NM, but now the Left Bank plan only calls for about 100,000 SF of retail, of which 50,000 SF is a grocer. That isn't a ton of retail space.
University Park Village and West Bend (across the street from it) are one cluster of apparel retail and presumably Clearfork will be another. Those two clusters will certainly compete, although there is common ownership (Simon), which will likely mean that the two clusters will be friendly competitors.
Regarding Clearfork competing with the Near West Side/ Cultural District, I imagine Clearfork is going to be a quasi-urban district, when complete, that will be be in part a mall substitute. The costs of rent and operating expenses there will be so high that it will be almost all national chains, whereas there are a lot of smaller, independent, local and regional shops around 7th Street.
Very different target tenants and visitor experiences. The Domain in Austin is a great example of how Edwards Ranch's Clearfork will likely look and feel. It's all brand new, and it feels that way.
I think its good for Fort Worth to have multiple districts and destinations. It is, however, a shame that Clearfork doesn't appear to have any potential connection to any future transit. It will be a walkable district but the only way to get there is to drive. Ultimately, Downtown, the Cultural District/Near West Side and The Near Southside will all be connected by good transit, which will make them great for people living in the central city and for visitors to Fort Worth.