I love The Golf Club and agree that it's a viable model - however, the developer had a HUGE advantage there - they already had a lot of the tools to create golf courses and the mechanics of golf itself because of years of doing outsourcing work for EA's "lesser" versions of Tiger Woods (i.e. porting a version to the Wii so EA's main dev time is dedicated to Xbox 360/PS3 version).
Plus, the TGC dev team self-published, did early access on Steam, and went very wide. And while TGC appears to have been successful, I don't think it's been a massive runaway success in terms of revenue. I sure hope it's been profitable, because I'd love another update or new version in the future.
Anyone starting today with tennis basically has to start from scratch. That's such a huge risk in an unproven market that I don't see anyone doing it.
But I hope I am wrong!