Old post but here my experience:
Back between 2010 - 2015, I worked in a mobile telecom company in Portugal - TMN - as a Core Network Engineer.
Back at the day we had when I was admited 2 networks:
2G was being provided by Ericsson from Coimbra to the North of the Country and Motorola for the rest while 3G was NSN or Nokia Siemens Networks. The core network was all NSN.
Then like one year after the 2G network was replaced by Huawei (they won the contract because they were basically offering the hardware together with the support contract, winning all the other brands competing, as there are enough reports of similar cases around the world, and the bean counters just rejoiced) and the 2G network were all decommissioned and replaced.
Then 4G arrived and NSN were chosen, with Cisco behind as the core for the data and VoLTE implementation (at the time it was a new technology, who make in the first years, even after I left in 2015, for the data to be handled in 4G while the calls would make the phone "fallback" to 3G).
By the way the test phone at the time for such thing was a non released Nokia (Microsoft) Lumia prototype that never saw the light of the day.
At the time it was talked that with the 4G being deployed and VoLTE, 3G would die eventually, while 2G would stay as a emergency/fallback technology in case something very grave would happen.
Now from what I know the network changed again from NSN to Ericsson for the 5G and then again to Huawei while rollout was being done, but I wasn't there already and don't know the real reasons why, but since the company was sold when I was going, I would say that it was again by how Huawei does business.
I don't know if such will happen in TMN (now MEO), by leaving only 4G and 5G as dominant networks while decommissioning both 2G and 3G, but in my view it is a bad move. The mobile phone market at least in Portugal is not as in the US where people change phones as you change clothes.
Salaries are not as high, taxes are a lot, so phones are kept for a lot of years, specially if they were expensive. 2nd hand market is also strong. Plus in my view you need to have a reliable, mostly failure proof and well developed (known) technology in case "sh*t hits the fan" and all the newer techs kick the bucket, kinda like Analogue Radio is still used as a fallback for emergency announcements in case of a catastrophic event.
So seeing this by Vodafone, they really are confident on their network and customers acceptance/penetration of newer UEs (User Equipments, how a mobile terminal is called in telecom).