UScellular has nearly exited the wireless market, after signing its latest spectrum sale agreement. Some 70% of its previous spectrum portfolio has now been sold off, across at least four deals. The incumbents are shoring up gaps in their networks by acquiring assets from distressed regional MNOs. The uncomfortable truth is that the major MNOs are the ones distressing the smaller MNOs in the first place, and so while UScellular attempts to put a positive spin on the sales, this is a carcass trying to remain on good terms with the vultures. Back in May, T-Mobile signed a $4.4 billion deal to buy the bulk of UScellular’s wireless business – but only around 30% of the rural MNO’s spectrum. Last…