Earlier IAF sqns had just abt 18 aircraft each. And 42 sqns were calculated to be adequate to take care of two front war in 1967. These figures for 42 sqns are from 1967. We also used to have IAAF-Indian Auxillery AirForce which was also known as weekend Airforce. It had seven sqns and was manned by civilian and retired pilots of IAF. These seven sqns were merged with regular IAF to make it a total of 42 sqns. However, Now IAF wanted to increase the sqn strenght to 54 sqns but due to IN taking over security of its areas the strength will remain 42. But IAF did something even more smart. They have now increased the strength of each sqn to 21 aircraft of which 18 will be available online and 3 will be war reserve. This way they got additional 7 sqns.The basis you are assuming is of numbers based on earlier calculations of 42. There is a reason why the IAF is scrambling to ramp up numbers by getting in second hand jets. Not just numbers but also availability. I believe, there is/will be a clamour within the IAF to increase squadron strength to approx 52. @vstol Jockey would be interesting to hear your insight on this.
In this scenario, I don't think we will have too many options. The IAF does not want American fighters. Tejas will come in. Mk2 whenever it is ready.
AMCA and TEDBF all are still up in the air.
There are only 2 new fighter options. Tejas and Rafale. Rest all, till one sees them on ground....ball talks.