I happen to have a Takamine EN10 which I bought in 1990 for around 800 pounds.
Great sound and all that but the frets had to be replaced twice since then to keep it playing without buzz......low action and soft frets etc....
The music repair people considered me a heavy player but I'm not in Hansards league...he must have played it constantly for 20 years to get to that level of wear through the soundboard.
If it sounds good he's better off leaving it alone as the soundboard is impossible to replace without destroying the tone of the guitar. Older guitars sound better with age because the wood becomes more flexible with age and better able to resonate the sound of the strings than new guitars.
Steve Cooney, the Australian-born Irish music guitar player is also noted for his percussive style which wears out soundboards.He also plays wornout guitars without care or comment and they sound good, which is the main thing.