ElementTree has always been in 3.x. I believe NumPy and SciPy are finally making the leap just about now.
‘Just now’ is hence a bit too late, but it is correct that many users have only been able to use Python 3 some four to five years after 2008.
If he had actually addressed the important questions in Python3 (first being getting the majority of people on 3 quickly by getting the major libraries ported quickly, second being addressing the GIl in either 2 or 3 (if the GIL had been removed in 3, I would have much more strongly considered it).
If either of those had been addressed, some of us (who are influential in the area) would have adopted 3 and prosetlyized it. However, I lost so much confidence in Python after the 2 to 3 transition that I've decided to actively non-prosetylize it.