Filip Dewulf the former belgium player writes on his twitter account that Arno and Paulo will play an exho against Darcis and Goffin in november in Andenne. So another exho after the one in september with Nico Mahut.
I just look at the senior tout website and Arno is eligible but maybe not enough famous ? Santoro play it despite not a great achievements compare to the others but his job seems to be a little bit playing these exho or tour
To be eligible to compete on the ATP Champions Tour, players must have been either a World No. 1 singles player during their competitive playing careers, a Grand Slam singles finalist or a singles player in a victorious Davis Cup team.
So for the senior tour I'm not sure but there is some exho with formers players during all year and the Grand slam.
Boltz who is one of the new guy training at FFT center had famous partners including Arno since his arrival. An article on that boy in a local newspaper and a pic with Arno. The young was impressed by the intensity and the sweat of Arno It seems that the new retired is still fit