Agni-5 came into being just after 3 years its realisation started at DRDO which in past had been way longer for missiles. Except for initial developmental trials, rest other are regular trials which happen after frequent improvisions like composites, seekers and navigation systems or within exercises and trials by armed forces. They can't be rendered as a part of development cycle but MoD's procedure to induct a weapon (not accounting how much official info released for strategic weapons is often true; they often enter service way before confirmation).Ummm... nope. Agni 5 was first tested in 2012 or so. It is still being inducted with last development trial happened in end 2018. Don't know when user trials will start and end.
Agni-5 has been deployed already 2 years ago and
It hasn't made that missile obsolete or outdated. In fact, still falls among modern missiles and which are seen as good to have by most countries.AIM120-c5 was intucted in 1990s. Thats about 25 years ago. US has moved to c-7 then D.
As told before, you are now shifting comparison with US who was first country in the world to introduce this generation.
Still, Astra with all its equipment, is among quite good A2A missiles; equivalent or more than AIM-120 C5 version. SFDR we are developing will come in next decade on our fifth generation fighter will then be equivalent to upgraded AMRAAM and PL-21, far from being obsolete, instead will be among world's best.
Terminal (especially) and mid-course interception abilities are essential to shoot down MIRVed warheads. Since MIRV separation can only take place inside atmosphere, it has to be killed when it is out of it. Intercepting targets at this much height is only challenge you have to be over to become expert in anti ballistic missile tech.Errr... ASAT okay, terminal abm okay BUT mid course is highly speculative. And mirv intercetion is sure unlikely.
And yes, without realising these technologies, you can't move ahead to develop an ASAT missile at first place. India has realised mid-course & terminal interceptions in 2016 and again in 2017.