There could be more French schools in some places. However, we can't always rely on the typical little box that defines a school. There are creative approaches. Yes, all francophones should have the option of learning in French and the minimum number shouldn't be too low.
For example, when I was a school counsellor, I voted to open a new school in our town of Barrie. As I was saying, 25 to 30 non‑Catholic people were entitled to a French‑language education. Hence my proposal to open a school to serve those 25 to 30 students, knowing that their numbers would increase. Shortly afterwards, the superintendent came to us with anglophone admission committees. I let him know that, no, I didn't really want to open an immersion school. He replied that we would look crazy if we had fewer than 100 students. For him, it wasn't a matter of serving students, but of not looking crazy if we had fewer than 100 students in a school.
As a school counsellor, I was prepared to fight until the end for those 25 or 30 students. We opened the school, and 92% of the children in grades one, two and three were new rights holders identified on the spot. The remaining 8% had already entered through the normal admission process.