Imagine them all over the world. And connections changed randomly or people could switch. And with sound, and with automatic translation.
This might be a powerful tool to unite the world.
Sorry if this sounds impolite, but please no.
This is taxpayer money spent on a project, that is, at best, a fun novelty for the first time you see it. Most people living there see it once, look at it, often without even realizing where the other end lies, and ignore it for the rest of their lives. Source: that is my exact experience with the Vilnius portal, as someone who often commutes to Vilnius by train.
The money that was spent on this would have been far better spent making the area around the Vilnius portal, or the nearby Vilnius train station, nicer.
As an alternative, I would suggest improving the EU identity through social media, education and interconnectivity through improved infrastructure, things that, as far as I'm aware, are already being slowly implemented through other projects.