You
will have customers coming shortly.
http://www.google.co.jp/search?hl=ja&rlz=1C1GGLS_jaJP291JP303&q=site:*.co.uk+"will+have+customers+coming&btnG=??&lr=.
'have' means to possess (not a causative),and 'coming' is a participle describing 'customers', right?
Thanks.