I would hold off in hopes that The Impossable Project works out okay because they will be producing Polaroid 600 film on the original Polaroid equpment. You can still buy Polaroid film at places like CVS.
Helping to save analog photography one exposure at a time
fuji instax mini/polaroid mio is a wonderful camera and film.the larger size is bulky and awkward (the instax 200.) the film is wonderful, great colors, not really like polaroid but a different kind of charm (i love it.) really oversaturated color. i buy fuji instax mini film from hong kong on ebay for cheap.
Don't forget that the impossible project will not be producing Polaroid-quality film. They are planning to produce a film with imperfections, that will give different results with every picture, sort of a film Holga.
Instax film (like all Fuji instant film) is manufactured to the quality standard that we are used to, viz: sensitivity, color balance, and saturation very close to the same from picture to picture, pack to pack.
So they are different films (assuming Impossible ever gets off the ground), filling different functions.