"Odds are you've binned the iPad"
Hardly - seems a bit of a stretch - binned rather infers you have got rid of the iPad - well the survey shows they may be using the iPhone proportionally more but do still use the iPad - not that they have binned it completely.
The survey also does not seem to give any indication of how the stats were generated or how many people were involved. For example I may use the iPhone 6+ more frequently to do quick searches etc. but would still swap to the iPad for longer browsing etc. So if it's based on number rather than time it may not be very representative.
I think in reality people may use their larger screen iPhones more (as they are more convenient) but the survey did not actually ask anything about 'would they be prepared to get rid of their iPad as a result' - suspect the result of that would have been a lot lower.