Let's say for fun, we "decide" to make a trip from, say, Salzburg to Rome on NightJet EN295 that leaves Salzburg 2200h and arrives 0925 next day.
While the one way fare of €139,00 is cheap enough (by air according to a quick Orbitz peek is €235), that is one Berth in a three Berth Cabin (higher than Couchette). Despite all the NightJet propaganda, that is the highest accommodation that can be booked on the web.
A peek at their site
http://www.nightjet.com" onclick="window.open(this.href);return false; shows Single Deluxe Rooms complete with private shower, but, if what they offer on the web is last word, they sure aren't on that route.
No business traveler, will put up with that, or for that matter, certainly when compared with a backpacking millennial, will this single affluent traveler.
The railroad and Wagon-Lit "Orient Express" is gone. Away from flashy brochures and a nice livery that puts lipstick on the pig, it is simply an Econosnooze product - again on this Salzburg-Rome route.
Europeans, including business travelers, were I'd say even into the '80's, willing to have a broom closet hotel room featuring a walk down the hall to the "WC". I'd think today they expect the same amenities as does a Stateside traveler.
All told, I think the OBB managers had a bit too much Gruner Veltliner when they finalized this business plan. European Sleepers of the six bunk per cabin Couchette varietal will still be around so long as there are young people backpacking over there, but to them such a Sleeper is simply saving €€€ over a hotel.
Finally in all fairness, the Single Deluxe cabins do exist; they are presently available on the Bregenz-Vienna line, or otherwise the length of Austria.