The small one in your first link is a modern PCP (phone cabinet). The larger one with the air vents is a Huawei FTTC 288 cabinet connected to the PCP.
The small one on the left in your second link is an old PCP, almost certainly still active. The larger squat one on the right I have no idea. I doubt if it is BT or Virgin Media. Not a clue sorry.
The third one looks like a small modern PCP, so as you surmise, probably to take over EO lines. Unless the latest combo ones (PCP+FTTC DSLAM) don't have air vents - I haven't seen a picture of any. I'd expect to see small FTTC cabinets coming near to them.
The indispensable man or woman passes from the scene, and what happens next is more or less the same thing as was happening before.
My broadband basic info/help site - www.robertos.me.uk.
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UnLim Fibre (FTTC). Sync 57676/14040kbps @ 600m. - BQM