Los Angeles station KCET's announcement on Friday that it is canceling all PBS programs is a dramatic, all-stakes-on-the-table gamble. KCET is gambling that, without hefty payments to PBS and substituting a new lineup of independent and international programs for the PBS network feed, it will be a smaller but sustainable public service broadcaster. For its part, PBS is gambling that KCET cannot possibly go through with its plan and will have no alternative but to pay the substantial dues required to keep PBS programs on the station…….