Fotis Karonis sees everything before that as "proof of concept." He's Managing Director of Mobile and also IT, where he's advancing Software Enabled Networks. He believes BT will be first in Britain, implying the other British companies will be later. He didn't say the "first commercial" cells in 2020 will be many, so his date doesn't conflict with the 2022-2024 plan for volume mmWave from NTT's Seizo Onoe.
He acknowledges that BT still has a long way to go in LTE deployment. While they claim 99% population coverage with LTE, these maps from Open Signal suggest they are not using a robust measure of actual coverage. The map above is based on tested connections to LTE. Below, the 4G and 3G maps are side by side. Note how many places 3G is working but you can't even get 4G. That's strongly suggestive of either a crowded LTE network or optimistic coverage estimates.
Karonis is strong on the need for reliability, particularly as BT adds security services as customers.
Stanford Professor Paulraj has been particularly strong on the need for reliability as we become more dependent on telco networks. Everyone agrees that's critical for 5G, but we'll see whether networks are built to that standard.
In this video interview with Justin Springham of Mobile World at HWMBBF16, Fotis is clearly talking about mmWave as 5G but not Massive MIMO. At that show, I learned that both Softbank Japan and China Mobile on ordering thousands of Massive MIMO cells, getting 3X to 10X capacity improvements with better to follow. I think if he thought about it, he'd include Massive MIMO in "5G," and make clear when he's discussing mmWave exclusively. Here are the video and the two maps.