As crazy as this sounds, I count maybe 3 RB's in the world that are clearly better than Nunes (assuming he maintains/improves on his end of year form) and below 29 years of age. Hakimi (up for rape charges or something grim), Trent (not for us), and Kounde (think he just resigned or is about to).
The ready made RB market is scarce. Thus we must sign for potential, The Vanderson, Livramento, Gray, & Wesley types are probably the closest to being first-team quality. It seems Spurs are interested in Grealish so Gray could be an option. But I doubt he walks into the team. Same with most of these guys.
I think City are doing the right thing here by not panic signing some 30 year old stop gap RB or overpaying for some youngster that is no better than Rico Lewis. Khusanov or Reis could be considered world-class RB's next year for all we know. No issue with us waiting for the one. The panic is well overblown.