Not to mention that not all trainzers have a continuous internet connection for trainzing.
ajrf,
The date of smash's original post which you quoted is nearly two years old. A lot has happened since then. The proposed Trainz subscription, which would require an internet connection while using the game, is now more likely to be only for multiplayer Surveyor, not for normal single user Surveyor. This, according to posts in these forums, will be to cover the additional server and bandwidth costs incurred by a multiplayer version of Surveyor. And, if my memory serves me correctly, the subscription would only be required while you are actually using the multiplayer service. If you go back to normal single user mode then no subscription is required. Hopefully, none of this is "just speculation".
I do not know if a DRM (or similar "internet free") version of NEXT/Trainz 2018 will be available. I would be somewhat surprised if it was not, for the reason you have stated.
I just hope that they do not get pressured into an early release because of contractual or other obligations, like they did with TANE.