Maybe he'll inspire her to stare Serena into submission. That's the only thing I can see Connors doing for Maria. Maybe work on her footwork a little that might help her a bit against the rest of the tour but she's already made a lot of improvement in that area.
I can't see any of today's folks being coaches in the future. Then again, like Litotes said, did anyone see Lendl and Connors as future coaches? Maybe Hewitt, I can see him as a coach. I would imagine someone who's spent the majority of their time in the 10-30 ranking places would like to come back on tour for unfinished business through a younger talent. So maybe someone like Isner, or Monfils. Not really today's "greats" but in my opinion they could be successful coaches of the future.