The big rip will happen if the dark matter/energy is not replacing the "space" in-between. I'd say currently observations are that energy/matter to fill in that empty space cannot come into spontaneous existence... BUT...
As we don;t know what the dark energy is, the force driving the expansion etc, I say there is still time to find out if the big rip is a certainty, or something else is possible.
Theoretically, there does not seem to be anything preventing matter from appearing in the comic quantum foam in the big empty space left by a "big rip", so why would reality wait until then, and not be doing it small scale now?