I think it's rather a pity that the revitalised French overnight services only provide couchettes and not private one, two, or three berth sleepers. I suppose the latter are not considered to be viable any more.
Yet they seen to be are viable for Nightjet - 2 sleepers in a four coach portion to Brussels, and two in a train of 7 to Paris, both also including seats as well as couchettes. .
I suppose viability would depend at what price they were pitched, and availability of suitable stock could well be an issue particularly as these days some en-suite provision might be seen as a must
In the past there seemed to be a great variance from route to route between the balance of couchettes and sleepers in France presumably reflecting different patterns of demand.
e.g as late as 1979 'le Train Bleu' was still conveying only sleeping cars (by 1981 couchettes had been added) although there were several other trains on the same route conveying a mix of sleepers, couchettes and seats, and the former Calais to San Remo (later Ventimiglia) sleeper(s) were by now on the 'Flandres Riviera' along with couchettes together with portions of couchettes from Lille and Amsterdam, the latter attaching sleepers from Brussels (and running multi portioned on busy dates). I recall seeing the main Toulouse to Paris overnight train in the same era with a formation which has stuck in my memory, 2 x T2 sleepers, 2 x First Class Couchettes and 8 second class couchettes. In 2004 The Flandres Riviera was in its dying stages, just Lille to Nice (or Ventimiglia - we got off at Cannes so I can't remember the destination), one T2 sleeper and five or six couchettes. Wonder of wonders we were able to get home comfortably in a day from Cannes courtesy of TGV and Eurostar which tells at least part of the story of the demise of such trains.
A resumption of some sort of overnight Paris to Italy offering would also be a plus. I recall my first experience of the Palatino in the early 80s was an eye opener - 3 sleepers EDIT: 7 (not 5 as shown earlier) couchettes for Rome, and two sleepers three couchettes for Florence - flus one first class seated coach and the Grill Express for Chambery, load 17. By 1995 when I travelled from Pisa to Paris it had of course been split in to separate trains from Rome and Florence, with the Rome train now 4 sleepers and 9 couchettes. Obviously demand fell off over the years but I do wonder if today's pricing structures might have made a difference.
SNCF are planning to get new sleepers as part of their revival.
This came in as I was finalising my response, excellent news.