In Europe sleeper trains have become somewhat extinct. High speed rail is just so fast and Ryanair so cheap, they became unprofitable.

However, there seems to be a revival going on. Especially the Australian railway operator (OBB) is investing a lot in their Nightjet trains. Some of the trains allow you to take your car with you.

I'm not sure if they are profitable, but they seem to be fully booked during the summer months (we had to book 2+ months in advance last year)