Yes, God's elect cannot fail in the end, whoever those might be. I suppose, according to the above, NO ONE can be said to have "failed"... However, on subject, theologians have debated over the place for infants PRECISELY because hell is meant for those who choose to reject God - AND heaven is meant for those who choose to believe in Christ. Since God desires all men to be saved, I would agree with most theologians that God is not bound by the sacrament of Baptism and will not condemn infants to hell - although they also may be kept from perfect union with God, as well. We rely on God's mercy in these cases.
Regards
That's an interesting way to put it, and I've never thought of it that way before. In the end you're right that the whole thing is left up to God, and our hope is that on this issue our view of what He will do "happens" to be consistent with our sense of "justice". :)