After saying that if Fringe kept 100% of its Thursday ratings once it moved to Friday that it would be a big win for Fox, Fox entertainment president Kevin Reilly then lowered that to 90%. Then he lowered it to 80%. But 80% of what? If it was against the 1.9 adults 18-49 rating Fringe was pulling at the end of its Thursday run, that would work out to be around a 1.5 rating. But remember, Fringe had a 2.0 rating or better adults 18-49 rating for three out of its first four Thursdays. I wouldn't take Reilly's words to mean Fringe is a lock for a renewal at a 1.5 adults 18-49 rating.
Others have noted that the tweets by @MaskedScheduler don’t make it seem like Fox is particularly happy with a 1.5 (or even a 1.6). And check your “who cares what some random guy on Twitter says” at the door. When not on Twitter, @maskedscheduler is an executive vice president at Fox who also happens to be in charge of scheduling.
On the plus side, I believe he is genuinely a fan of Fringe and not just because he works at Fox. But without saying it explicitly, the implication seems to be that Fringe needs to be around a 1.8 adults 18-49 rating.
My guess is that a 1.5 isn’t good enough. But I’d also guess as the weather warms up and daylight saving time returns, Fringe’s ratings will slip below a 1.5 and end the discussion. In fairness though the 1.6 adults 18-49 average through six episodes is better than I expected, but not quite good enough to keep it "on the bubble."