If he managed for 10 years on a P4 then he should be ok with either Ivy or Haswell for the next 4~5 years. But, if in the future his requirements grow beyond the system it makes more sense to upgrade then, rather than throw more money at the system now in hopes of making it futureproof.
Haswell isn't significantly faster, but its about 5% better, plus the i3 4130 has a higher clockspeed than the i3 3210 (~6%). If you are ready to spend 4k more for an i3 over a Pentium G2xxx for a 10~15% improvement, do you not feel that a ~5% improvement for only 200 rupees more is good value? Another plus point would be that since its a newer platform, if your mobo or proc have problems in the next few years you might have better luck getting replacements for a more recent platform.
An A10 is just an FX 4xxx with a good IGP. An FX 6xxx may top an i3, but I don't think an FX 4xxx will do well. And since you're planning to get a dedicated GPU in the future, the A10 IGP becomes redundant. Not to mention the FM2 socket is already dead.