This is a big problem, what will replace green PIC?
'Mantitor' is what is being sold over here at the moment, this is a similar product, which I believe is manufactured in Brazil, it burns at a rate of about 10 to 13 seconds per foot. However, there have been a few mixed reviews about its reliability, but there is little else on the market.
One of the companies I work with are importing a new waterproof fuse from China which is supposed to the the job will keep you posted.
Of course there is always slow burning Bickford safety fuse, but this means a bit of a re-think of your rigging practices will be needed.