Interesting, I've got the opposite experience.
When taking into account the time required to get to/from the airport and the time required to actually get on the plane, it's just as fast to take the train. Taking into account comfort, stress, and effort required, the train wins by a very large margin.
If you book in advance, €35 tickets are very easy to get, and sub-€60 aren't uncommon either. The article compares last-minute train pricing with the cheapest air fares. If I want to take a plane to Paris tomorrow, I'd have to pay €366 as well. For virtually any date, booking a train is going to be cheaper than booking a plane.
If anything, the biggest problem with high-speed trains is that there aren't enough of them, and that they share too much infrastructure with traditional trains. They are not killing low-speed trains, reality is. Even without high-speed infrastructure, many of them would no longer exist: for longer distances, air travel is simply in every way superior. They are just far too slow and far too uncomfortable to compete.
Besides, actually running those trains is an absolute nightmare. The article suggests giving them priority in order to keep the timetable. In reality, in The Netherlands large portions of the network is transitioning to a train every 7.5 minutes. Any delay whatsoever is unacceptable: having a delayed long-distance train could result in the cancellation of literally dozens of local trains. Overnight trains could work, but that's not really desirable for medium-distance. It was fun while it lasted, but they are just no longer viable.