Backhaul generally isn't the bottleneck - you have fiber to the towers, and you can bump the capacity of that with comparably cheap hardware upgrades - however, the available "air bandwidth" per cell is pretty much a hard limit, and to go beyond that you need to build more cells which either requires more frequencies or more towers, which both are very expensive and time consuming.

Perhaps it's different in USA, though, the geography and population density differences mean that the backhaul problems are different than in Europe; but here the bottleneck is on the radio side.

>> They'd have to upgrade the backhaul too though to take advantage of 5G capacity.

THIS!!! Even if more sites are added, each with their own 10/100gb fiber run - it's still running to the main circuit for a region. That circuit isn't changing(in the near term), this will just consume more of it. Regions without colossal backbone access that are already bandwidth constrained will remain bandwidth constrained.

I’m sure they would. For all the faults of telecoms companies, they generally don’t like spending a massive amount of money on upgrades that do nothing.