Someone

set z_name1 "set z_nextname vstr z_name2; name ^1nick"
set z_name2 "set z_nextname vstr z_name3; name ^2nick"
set z_name3 "set z_nextname vstr z_name1; name ^3nick"

set z_namenext "vstr z_name1"
bind x "vstr z_namenext"