Now, a few things come to mind when thinking about this.
The new “standard” is supposedly higher than previously considered as the standard. That could mean fewer children passing, unless teachers get better at teaching to the new test, so a large group could need some kind of defined intervention in year 7. This group will vary in size from area to area, depending on the local demographic; possibly from near zero to a majority.
It could be seen as an action on Secondary schools to ensure that they play catch up with a specific group. However, this group will be largely those children who have special educational needs, some of them quite specific, which may preclude them from achieving at the end of year 7. There has been no mention of what might be the outcome for those children.
For the 26 years of the old National Curriculum, with level descriptors providing the basis for decisions, there was always a dispute with Secondary schools about their willingness to accept the outcomes of Primary assessment and testing, even with regard to levels 3 and 4, in Maths and English. They were deemed, by colleague professionals, not to be the same in the different contexts.
I have to say that I can see the same happening over the next few years, as Primaries develop their own assessment schemes and as the outcomes of the National assessment tests may, or may not, validate those internal decisions, so that, on entry to Secondary education, children will be faced with a further battery of internal tests to enable Secondaries to create their own baselines. This will also happen to in-year entrants, to enable decisions on placement.
In reality, it is likely that in the near future, children will face more and more testing, until some settling takes place.
All this could have been avoided, with a national “tweaking” of the wording of the level descriptors to be used as “capability or progress descriptors”, coupled with the imperative to only use words in discussing progress with children.
Numbers are for teachers, as data; words are for learners.
A national portfolio of exemplar outcomes across all subject areas would be possible, as demonstrated by the many websites that encourage work sharing. This would enable local moderation against national benchmarks; something that may be lost in the next period of time.