Yup, this is another idea I've heard floating around. In some situations where fiber backhaul or line-of-sight is not feasible, Starlink could link their ground stations to these hard to service locations extending the reach of existing backhaul.
Then the 4/5G can be set up using a mixture of fiber, line-of-sight or Starlink backhaul, depending on the situation and location.
Of course this is another way that Starlink might be able to win some of these contracts. They could set up (or work with a partner) mini 4/5G networks in these rural areas and also use a mixture of fiber and Starlink backhaul. After all, they still need fiber backhaul for their ground stations anyways.
Starlink customers end up not needing to buy the current, expensive hardware and just use relatively inexpensive 4/5G modems.
I've heard this isn't possible with the gen 1 satellites, so still a theory until the Starship program is off the ground.