3G
"with 3G coverage and data tariffs improving daily, the service could find itself redundant before the technology does."
Yeah, improving daily - they could hardly get any worse. I've yet to get a signal at all with my Virgin 3G modem on a Virgin train, except for the couple of minute while it's pulled into a station. At least that's long enough to open a few pages in FF tabs, but that's hardly what I signed up to so-called "mobile broadband" for.
Will Virgin Mobile customers get wifi access on Virgin trains too I wonder? It might be the only way I can contact the outside world, I certainly never get mobile coverage on Virgin, while everyone around me is chattering loudly into their phones.