The I6 can be sometimes seen on the Brussels – Luxembourg and Ostend – Eupen trains.

I haven’t seen the I10 ‘resto’ in a long while. I believe it still exists, but the kitchen is not equipped anymore.

In 2019 a special train consisting of only first class carriages (I6, I10 and I11) was used for the King and Queen. Catering was provided in lunchboxes. The Resto car was not used. https://tripbytrip.org/2019/10/15/special-royal-train-for-king-philippe-and-queen-mathilde-of-belgium-going-luxembourg/