Indoors without a flash, FP-3000B is useful in a Polaroid camera and paired with Delta 3200 120 film it is useful for proofing shots in a medium format studio camera.
That said, FP-100B is more useful in many ways. It has better reciprocity characteristics, is sharper, seems to have a deeper black. I have a bunch still. B&H seems to have it in stock. In truth the head of Fuji USA said he is worried that they can't get rid of their stocks before they expire this year so I suspect there will still be some for time to come. Honestly, like the rest of the stuff they sell the expiry dates are overly conservative, even if you don't refrigerate your instant film it lasts well past the expiry date with no ill effects in my experience.
I will be sad to see it go but I'll shoot 3000B after that; even outdoors it works with a small aperture and fast shutter speed though sadly you can't as easily get nice DOF unless you use filters. ND or deep red filters work well with FP-3000B however to let you use a wider aperture for narrower DOF so all is not lost.
It is our fault sadly; we obviously didn't buy or shoot enough FP-100B for production to continue. Sadly it actually stopped being made quite some time ago and despite my begging, Fuji won't restart production Let's buy lots of FP-3000B so it keeps being made!