Look at the cost of IVF: According to http://www.momjunction.com/articles/much-ivf-treatment-cost-india_0074672/ it is $450,000 Rs, which is $6,000 dollars. IVF is a prerequisite for the sort of genetic tampering we are talking about, unless you want to use rabies as a carrier. IVF is widely practiced and has few barriers to entry, making me think it won't get much cheaper. That is a lot of money for many parts of the world. To think this cost will come down in the next 10-20 years significantly requires believing that significant advances in automation of the process are possible: that might be true.

Financial incentives to have smarter children are likely to work better in those regions where $6,000 is a lot of money. It's possible that combining both strategies works even better.