A 51% attack is way too probable for my likings. This should be issue number 1 to fix.
We got to 51% (again) and was there an attack?
No there was not but the probability of an attack is still too high. Just because something does not happen does not mean it is impossible.
I would argue that the entities that could launch a 51% attach (large pool operators, cloud mining sellers) have too much of a vested interest in the Bitcoin economy to launch a 51% attack and would end up loosing more then they could steal in such an attack.