Andy Sutton, Principal Network Architect at BT, sees millimeter-wave backhaul playing an important role in 5G networks. 90% of GSM networks used microwave for backhaul, but fiber became increasingly important in more recent systems. 

Sutton notes that E-band radios today can deliver 6 gigabits with 99.99% reliability. Recent regulatory changes will increase the spectrum available and data rates. That should be sufficient for most European 5G sites, which are primarily mid-band or low-band.

Verizon's Glenn Wellbrock, Director of Optical Transport Network Architecture, Design, and Planning, also sees an increasing role for wireless backhaul and fronthaul. Fiber is now 90% of Verizon's 5G backhaul, but he sees that microwave may double and backhaul 20% of sites.

Governments are being pressured to provide rule changes and cash for more fiber, because "fiber connectivity is essential."

Fiber is great, when affordable, but top engineers at the most advanced carriers agree that wireless is often a good alternative.

Muntazir Abbas in Economic Times quotes Tower and Infrastructure Providers Association (Taipa) Director General Tilak Raj Dua. “In order to make 5G a success story in India, it is essential to invest on network densification heavily through provisioning of fiber." That's lobbyist talk, not factual.

Fiber will generally be required in mmWave 5G, but mmWave is well under 10% of 5G sites worldwide and even less in India..