Yeah I agree.
When my brother and i were really young our parents used to speak both English and Dutch to us. They stopped talking English to us when I went to school so I must have been about 4 and my brother about 2. But when I picked it up again when I was 11 I had no problems dusting my English of to somewhere near fluent. (though u would laugh at my attempts to speak it probably, lol) My brother is pretty good at English as well.

When your kids are young they will prob mix them up and produce half english half french sentences, but when they get older that will get better too.
Every study shows, the younger you start learning, the easier it is to pick it up.

There are sometimes votes to start teaching kids english and dutch at school from age 4 and possibly also another language like french or spanish. Though i don't think that will happen lol, as the teacher would claim its hard enough to learn them proper Dutch, let alone 2 or 3 languages at the same time... Also the teachers would have to be perfect in these languages too --> if you teach it to the kids wrong it will be near impossible to fix it later on. Esp the pronouncing, that is.

Either way if you talk both English and French from the start it will work out fine I'm sure!