So what Happens now?
IAF has 33 Sqds at Present
6 Mig 21 Bison Sqds are supposed to retire over the next 4 yrs, While During this period we will induct 72 Su30 MKI and 40 LCA MK1(ie 4 + 2 Sqds). Thats 112 Fighters replacing 120 Mig 21Bisons which is fairly acceptable since these fighters will be a quantum leap over the Mig21 while still maintaining the Sqd level of 33
That figure dosnot take into account the likely attrition we might have during that period
The problem will occur once the Mig27 Starts retiring in 2017. IAF has some 87 Mig27 in service across 5 Sqds, The Rafale was supposed to replace all 5 Mig 27 Sqds and 2 Jaguar sqds , that 135 Fighters being replaced by 126 fighters between 2017-24.
The only other fighter we will induct in the 2018-24 period will be the LCA MK2, with MOD having ordered 83 of them
So you are looking at a further Shortfall of 60-70 Fighters or 3 Sqds by 2020-22. That would mean, we would be left with a fleet of 580 Fighters against a Sanctioned strength of 780, and considering IAF discomfort in the fleet falling below the critical 650 Fighter Mark , they will only have 2 options
1. Keep the 30+ upgraded Mig27Upg and 37 Jaguar IS/IM flying for another 3-4 yrs, since half the Jaguar Fleet will remain in service till 2030 , I see Chances of Jags higher than Mig27
2. Order another 50 upgraded Su30MKI, since HAL is already manufacturing the MKI, it can Deliver the new batch between 2017-20, once the present backlog of 72 fighters is cleared. This will allow IAF to completely phase out the Mig 27 and retire all 27 un upgraded Jaguars. IAF can also increase the order for LCA MK2 from 83 to 120
this wud allow us to maintain 34 Sqds