In my opinion, the demands make sense.
It is easy to see why European telcos invest less while having less long-term security and that building an infrastructure four times is not economic, especially given the large amount of antennas required for 5G.
Interestingly enough, they talked about building Open Ran Networks in the presentation. I saw that you covered the state of Open Ran Networks in this good overview and it would be awesome to get some updates. I would be particularly interested to understand if the industry is convinced by now that Open Ran is the future and it is almost certain that the networks of the future will Open Ran based. (This would make the infrastructure of 1&1 more valuable in case 1&1 cannot build their own network and need to sell it)
My take is that established companies are probably not open to share frequencies because that would allow a competitor to build their own network. Instead they could be open to allow a competitor access to their own network via national roaming/MVNO contracts. That is at least in line with the 1&1 Vodafone Deal and what Della Valle said during the event.
Overall I believe that the likelihood that 1&1 can never build it’s own network is growing. That does not have to be too bad for it though, as long as they get good access to other networks.