A multi year deal with Mata remaining in the club (perhaps working to become a coach, scout or some other cog in the club) is an excellent bit of news, personally speaking. I think he is an excellent personality to have around and he is our most technically gifted player currently. I'd say he can still do a good job for us on the pitch provided we find a good role for him to play... and off the pitch he's going to be great. This is rebuilding, too - rebuilding our club structure and DNA.
In terms of of what his role might be after his playing career ends, he seems to be a really intelligent guy with a lot of football knowledge and passion for the game to be played in the right way. And he is obviously seen as someone who should remain at the club. I think this is one of those deals that might not make fans happy, but is ultimately great for the club and exactly what the club needs.