I feel at some point you need to deal with the contributions of recent work on racial capitalism as it relates to the circulation of labour capacity.
That is, those scholars like Robin D.G. Kelley who build on the work of Cedric Robinson's Black Marxism to argue that the circulation of value has always depended on the production of social difference.
The idea that European civilization was constructed based on social differences (linguistic, racial, tribal, regional). The bourgeois who led development of capitalism came from particular groups, peasant from others, proletariats from others. The evolution of capitalism did not homogenize these differences but exacerbated them. As capitalism expanded, it reproduced differences elsewhere.
I mean, both you and Neil Smith accept that the circulation of capital requires the making of uneven development/differentiated geographic space. It doesn't seem farfetched that you could grapple with Cedric Robinson's ideas that capital circulation--via the circulation of labour capacity--likewise depends on the production and circulation of social different (race, class, gender, sexuality, ability, and so on).
Anyways, I'm not sure the most appropriate point in this chapter to insert it; however, this may be one place to include a paragraph.