I agree, as far as the vast majority of students are concerned. Some students, who may be more talented or more intelligent, can succeed even in late immersion programs, such as those starting at grade 6. I think that it is good to have choices, where possible, with various entry points. But eliminating the kindergarten or grade 1 entry point is definitely not a good idea.
When the decision is delayed and the parents have to decide about immersion when their child is in grade 3, the first question is always whether the child is doing well in English and other subjects. If there are any problems at all on that front, they have a tendency to think that the child should not go into an immersion program.
One school principal that I just spoke to told me that this reality was having a very negative impact in his school. The strongest students were enrolling in immersion and the weakest ones were staying in the English program. If the intention was to resolve the problem of streaming or inequality between the programs, it did not work. I think that the situation is worse now.