Thanks for the heads up about OT.
Here's my two cents about Mig-21 and it's replacements - A short history of Mig-21, LCA Tejas and IAF requirements.
1. Mig-21s were used as air-superiority fighters in the Vietnam war - that was ~50 years back! The Mig-21s were the early 3rd gen fighters (although nobody counted generations back then). India got a few Mig-21s before the 1965 war, although there were not enough training and pilots to operate them). India finally used the Mig 21s for good in the 1971 war and were impressed by them.
2. By the 1980s, the lack of maneuverability of the Mig-21 compared to the new PAF F-16s and their obsolescence led the IAF to buy the Mig 29s from Soviet Union (SU). The Mig-21s were relegated to support roles and were meant to be used as point defense interceptors. However, the relatively "weak" engines of the Mig-21 meant that they were not very good as point defense interceptors too.
3. The Mig-29s being delivered by the already crumbling SU were having engine problems and creating a lot of trouble in IAF. The only good 4th gen fighters the IAF had were the Mirage 2000s bought from the French. In the mid 1980s, the IAF asked HAL to develop a "Mirage-type" (western design) 4th generation fighter for them to replace the Mig-21s for interception and support roles. That was when ADA was founded and LCA was conceived. So, LCA was designated as the Mig-21 replacement from the beginning.
4. However, in the first half of 1990s, India went through one of the most potent forex crisis in it's history. India's credit rating hit new lows, the economy was in shambles after the collapse of the Eastern Bloc, India's largest trading partner. All defense projects were hit by the economic downturn and no new LCA funding were available. Only after 1995 when India's economy had started to revive thanks to IT boom, did GoI put in some more funds for LCA design and development.
5. Shortly afterwards however, the govt changed, BJP came to power in 1996. The tenor of India's foreign and defense policy changed, with the explosion of nuclear bombs in 1998. At the critical time of LCA development (1998-2000), when foreign collaborations and component buying should have happened, the western governments put in critical sanctions on Indian defense industries, leading to extreme delays in the LCA project in general and the Kaveri engine in particular. Remember, India's biggest problem/ handicap has been it's industrial manufacturing limitations - especially in terms of metallurgy and manufacturing process development. Engines are particularly affected by a combination of these two. There are only 5-6 countries in the world who have the metallurgical technology to develop a 4th generation turbojet engine - USA, Russia, Britain/ Germany, France and Japan. PRC is still trying to catchup and so is India.
6. By the time LCA was ready with the prototypes, the Kaveri had failed critical tests. So, in desparation (and to avoid more Russian engines), India turned to western sources - GE 404 was chosen for the prototypes and then for Mk-1. For the LCA Mk-2 a competition was held, between GE/ EADS - finally GE won the contract with the GE 414. The Kaveri engine development was decoupled from LCA and is being tried out through a JV with Snecma (Mirage again).
7. So, in summary, LCA was, is and should be the real replacement for the Mig 21s. The reason LCA is so late is as much technical as political. Actually it is ALL political - given it's history, it is a miracle that the LCA is still alive and kicking. GoI and MoD should hunker down, throw a whole pot of money, as much brains and indsutrial power as they can and see the LCA through ASAP - to replace the Mig-21s. With India's current ability and clout, we can do it by 2015. Mass production from 2016 (25-30 a year) would put ~250/ 300 LCAs in IAF by 2025, replacing all the Mig-21s, Mig-27s and even the Jaguars due to retire by then.