I thought it was the other way around 120 Jags and 150 Mig-27s. Anyway atleast 60 Jags out of total would be in IAF service for next 20 years of them 40 are less than 14 years old last rolled out in between 99 and 2002.
Yes you are right we have 200+ Mig27's but very few are air worthy mainly because of massive engine issues.
HAL has totally screwed up license manufacturing of Mig-27 engine and overhauling it
Dark secret behind mystery of the 'flying coffins' -The New Indian Express
So we have less than 100 in service rest are mothballed.
-----
100-110 of the 140-150 Jags being upgraded under DARIN-3 program so will have a good life.
37-40 were rolled out post 2000 and will have the same life span the Su-30's have.
HAL can make 40-50 more Jaguars under license if need be
Bottom line IAF has more Mig-27's than Jaguars but has more Jaguars flying and operational than Mig-27.
The Rafale when inducted will go first to replace Mig-27 and not Mig-21.