I just don't get the point of this
If a kid has failed to learn stuff, there is likely to be SOME sort of underlying problem here. Not necessarily special needs-maybe they just don't get breakfast. But that is what needs sorting. Otherwise kids are just going to be repeating the year ad infinitum...
Oh and I suspect it won't make a lot of parents buck up and say "Whoah, my kid is failing school, I'd better turn around our family life and spend an hour a day doing maths and reading with my kid.". No. Its going to make them, in some cases, pretty bloody angry with their child and the school, especially since secondary schools usually have longer hours, don't require so much parental involement, etc.
I also think that this is particularly unsuitable at age 10. It might perhaps make sense earlier, say top infants. But to keep a 10 year old in primary for an extra year when all their friends bugger off to big school just seems cruel.
This is also so daft in another way. I'm keeping my 4 yo out atm. He would be due to start school today. He is 4 and 7 days, has NO interest in reading/writing, loves stories and talking, and has a lot of interest in playing and bike riding. In short he is a fairly typical just-4-year boy.
Round here there is NO way for him to start late. There is no split intake, they all go in at the start of september, full time, regardless of birthdays. There is no option to keep a child down a year permenantly (I think this could be a good solution if done from day 1).
For us, therefore, I think not.