I'm glad they've been banned in Europe. It will be a perfect test. If bee populations recover--they should be banned elsewhere. If nothing changes, we'll know neonicitinoids aren't the main problem. Either way, we will have an answer.
There's some evidence that neonicitnoids by themselves don't affect bee health--see Australia, which has healthy bees and is also a heavy user of neonicitinoids.
Varroa infested countries might have no choice but to ban neonicitinoids, however, if the combo of the two is the prime cause of CCD.