I always thought the eurostar was a great demonstration how not to do it.
Shitty trains (compared to e.g. the ICE, TGV or Thalys), the stupid border control/security requirements with huge queues which meant you had to be there >45min early, they even mimicked lounges from airline travel. It's like because they wanted to compete with air travel across the channel, they thought "how can we make train travel the most like air travel" adopting most of the stupid things. I half expect them to build a separate train station next, somewhere in the middle of nowhere with extra expensive public transport connections.
Most of what you describe is not because they want to make train travel like air travel, but because the UK never signed the Schengen Agreement (so they need to check and stamp passports) and because of Brexit (so they need to inspect baggage for import/exports), unlike train routes between other EU/Schengen destinations.
I didn't notice a change in baggage inspections. The inspection occurs when you leave the terminal in London, but that's not blocking, like in airports, you just walk through unless you are one of the few unlucky ones. In 15 years it only happened to me once, and that was before Brexit (they mostly search for drugs and other illegal products).
They already did that; in France we have e.g. "Valence TGV" which is a secondary train station far from anything, whereas Valence already has a train station in the city center.
Shitty trains (compared to e.g. the ICE, TGV or Thalys), the stupid border control/security requirements with huge queues which meant you had to be there >45min early, they even mimicked lounges from airline travel. It's like because they wanted to compete with air travel across the channel, they thought "how can we make train travel the most like air travel" adopting most of the stupid things. I half expect them to build a separate train station next, somewhere in the middle of nowhere with extra expensive public transport connections.