Squeak, let’s analyze.
1) Extra boys born – unreasonable to assume enough to counterbalance.
2) extra boys dying – all the more reason to put more boys in the parsha.
3) extra boys going otd – ditto
4) extra girls becoming frum – ditto
5) extra girls buying into the torah only philosophy – ditto (for Torah only boys)
6) chassidishe girls crossing over – ditto
7) boys who are not torah only material being overlooked – ditto (for Torah only boys)
8) etc. The list doesn’t end there – can’t answer.
I think 1 is reasonable enough that you should at least be curious where it gets you, even if you think it is unlikely it gets you all the way. Especially if you believe in shidduch crisis because you believe in age gap.
As to many of the others, I don’t agree that we should solve the “not enough bnei torah” crisis by imposing costs on other parts of society. Suppose there are currently equal numbers of frum boys and girls, but 30% of the girls want bnei torah and only 20% of the boys are bnei torah. If you bring in the boys younger but don’t change the number of girls, you will be creating a shidduch crisis for non-bnei torah boys. Who says it is right to do that?
Also, while I concur that changing age gap can increase the number of boys even if the age gap is not the actual cause (suppose the extra boys born makes up for age gap, but more boys are not learners), I think it does make a difference in terms of the moral imperative on the boys to start dating younger even to their own detriment. If they are causing the problem, I could see more of a obligation on their part to solve it. If the problem is caused by too many girls having unrealistic expectations of what the learning lifestyle is, I have a very hard time accepting that the boys should give up years of their learning and possible sholom bayis to solve that crisis. How about abolish seminaries and solve that one.