Your last point if fundamental. "The Market"
Forgetting the current use of the OL for a moment because it only draws disparaging comments about retirees and any other persons who can afford the time.
Some of the reasons people travel Melbourne/Adelaide (not in any order).
- Sporting interests
- Visiting relatives/friends
- Attending conferences
- General tourism
In this age we would see most of these trips as time critical. Certainly business trips are as are sporting interests and conference attendance. Persons don't want to spend all weekend travelling to/from a crows match in Melbourne (certainly not at the moment).
Of the 5 points only point 5 would not be seen a time critical.
If the other points are not time critical persons may well drive so that their vehicle is available for use in Melbourne.
For some years I have been attending a church conference in Melbourne. While it was near the CBD my wife and I flew, we didn't need the car. When it moved to the outer Eastern suburbs we drove so we had the car to get from our accommodation to the conference centre.
Going to the Tennis and C'wealth games we flew because we did not need a car but had limited time. Only on our last tennis excursion did we catch the train. This was deliberate on our part because I wanted compare the OL with my Amtrak experiences.
IMHO, unless the OL can get between Melbourne and Adelaide in a morning OR afternoon it will not be viable as a day time trip; that means under 5 hours.
I am yet to be convinced that an overnight OL geared up market to be a travelling motel does not have commercial possibilities.
For many years I caught red eye flights with probably 200 plus business travellers and would have welcomed an overnight train that did not take too long and arrived on time. The poor Old Lady never quite made it. She did save my bacon with a fractious client on one occasion but that is another story.
Moving up market means they have to have up market staff delivering up market service.
Both a 5 hour daylight trip time or a revamped overnight service are dreams; possible but way out.
A DMU type service running each way daily with an under
8 hour trip might capture enough interest to be viable, even if people only use it initially for the novelty, it might catch on.