Very strange to say he will make a good coach. He might, he might not, is it worth tieing up money on a player for two years when the only justification is that he is a "good bloke "
Whose said/assumed he will make a good coach?
I think most people see him as a decent stalwart (5 years he's played for us in total), one of our most successful goal scorers in the last 20 odd years, he's been captain for a big chunk of that time (which suggests he's a good leader and well respected) and speaks well/sounds intelligent when he's interviewed.
You then add to the equation that he's this season (and last seasons) top goal scorer so from a playing perspective he's worth keeping.
Finally, you consider that if he's doing his badges its something that he wants to get into and has a passion for. He lives locally, kids attending local schools etc. So money *might not be his biggest short term objective allowing for a compromise agreement which works out well for both him and the football club as a whole.
There are many justifications in keeping him here. Not just because he's a 'good bloke' which according to you is the only one!!