Only the parents and grandparents of today's red eye air travellers know of the former overnight trains and they largely avoided the 'Aurora because 40 years ago air travel was the modern way of travel.
These days...air travel is generally accepted to be a necessary evil. It's no longer cool to be getting up at such hours to get out to the airport etc...it's merely accepted as a means to an end.
The XPT is no option as it serves a different market with a sole sleeping car that usually means a single traveller is bunked in with a total stranger...no dining options, nor a space to conduct informal meetings such as the former Lounge car.
Therefore I suggest the operators of the cars that once formed that service to get their collective heads and their volunteers, preferably the retired ones together...and advertise for more volunteers to enable enough cars to be assembled to form enough for two sets of trains that could potentially re-create the nightly service which would utilise full celebrity chef Dining car and bar service in the former Lounge car...the potential to grow this service is only limited by the imagination of the operator.
By utilising volunteers, now retired ex-railway people and others with a passion for providing great customer service in hospitality would enable the running costs to be reduced to track access charges, the actual operating crew, drivers and assistants, Guard and head conductor. The fares would be a premium, say from $350.00 each way to start off, however there are already enough expense account execs that would happily pay for a First class service that $350.00 upwards is a tiny price to pay for not enduring the early morning alarm clock.
Travel doesn't have to be both ways by train and the current air service can still be utilised for the return journey.
Again...I emphasise there are thousands who travel daily between the capitals and ALL of them have to face the grind of getting up at the un-godly hour of 04:30 in many cases to enable an early arrival at their destination and because there are so many, and because it's so easy to advertise an alternative means of getting to their destination, it would be easy to syphon a low percentage of those pax to travel on the overnight express, which at its former maximum load only ever carried 198 pax.
WE know AMTRAK still operate many sleeping car trains and in Europe despite the economies of operation there are still several sleeping car services:
https://www.seat61.com/sleepers.htm
and in England/Scotland...a new dawn of sleeping cars has arrived.
http://newtrains.sleeper.scot/
I feel the opportunities are there to re-commence a low cost operation by utilising the equipment that still exists which...with the size of the potential market that's offering can only grow and is only restricted by the imagination of the potential operator with their potential army of willingly trained volunteers.
Opinions and suggestions

Mike.