We are no longer an agrarian society and it is not possible to plant an extra row of potatoes because there is a new baby on the way . . . the Church has implicitly recognized the need for a morally acceptable means of birth control in today’s industrial urban society.
Exactly.
If that is the case, will the Church eventually allow condoms?
No, because the two are not in any way comparable. To use a condom is to contracept sexual intercourse, an act that is objectively sinful.
There is nothing objectively sinful about a couple abstaining from sex if they know that it will most likely result in pregnancy. The couple there is
obviously not guilty of contraception,
because there’s no sexual act to contracept! NFP is qualitatively, objectively different than contraception, so we ought not to equate them, even by analogy.
How about “catholic” condoms where every 10th one has a whole in it

? That’s what NFP seems like to me.
Let me help you understand something. The Church accepts the use of NFP
not because, “Well, technically, it’s still
possible for you to conceive.” If that were the case, then every form of birth control would be acceptable, since
no method besides abstinence (other than a hysterectomy or the removal of the husband’s testicles) is going to prevent conception 100%, no matter what.
So the possibility of conceiving has nothing to do with why NFP is moral. The use of NFP is moral because
all it consists of is measuring and accurately recording a woman’s fertility.
If the couple uses that information to avoid pregnancy, they do so by abstaining from sex when the wife is known to be fertile.
Obviously that’s not contraception,
since there’s no sex going on to contracept! Do you understand?
Now, that said,
of course such abstinence would be immoral if a couple uses it to avoid pregnancy altogether, indefinitely. But their sin in that case is not contraception - they’re not committing
any act whose
object is immoral - rather, the sin there is in their
intention.