Trying to make the old business model work is a lost cause I agree. You were happy when new golf sim versions came out regularly which is why the title of this thread that you created is what it is. But that's not going to happen for the reasons you state, though I think you've way oversimplified what's happening and appear to have concluded it's essentially over if that model can't continue. Apple Computer was essentially on the brink of going extinct itself until Steve Jobs envisioned iPhone and the rest is history.
Stretching out release intervals is a means of addressing and building the base of gamer golfers who appreciate realism in a golf sim, and making it economically more feasible. HBS has other titles to keep themselves relevant. Just two weeks ago I was visiting friends in California and one fellow I had played golf with had no idea a 'serious' golf sim even existed. He's stoked to pick up an Xbox and TGC 2019 after I described how the game plays. There are an estimated 60,000,000 players world wide to potentially market to and most don't even know about golf sims. Perhaps changing how they market might change the picture enough as well--this is the age of big data and I'm sure some db somewhere has my name on it as an avid RL golfer and gamer too.
Peer into what MS did with Flight Simulator. Their last release of FSX was in 2006 and they announced they were done with it as well as their feeble attempt at a sequel to FSX, MS Flight. They sold the core ESP engine to Lockheed Martin which proceeded to keep the doors open for DLC by 3rd party content developers supporting their version of FS called Prepar3D...FOR 13 straight years. Massive 3rd party content development. Suddenly, w/o warning at E3 this year, MS announced they're back in the game big time with what appears to be everything the flight simmer could hope for. The analogy is flawed but I am only using this example to describe how getting out of frequent serial releases can open up the door for other ways of developing product. I'm hoping other non-arcade titles continue to disappear and leave TGC poised to rein supreme as the only serious players golf sim.
Can you imagine the cost of creating Rory? It's hard to fathom really. TGC does not need to do this--they need to judiciously add DLC, ultra well done in keeping w/ their potential mission of being the go-to sim for serious gamer/players. DLC is just a way to keep people requiring newness interested without coming out with full new releases--I can see purchasing first class animations similar to what Rory offered. This adds some depth and can shape what the release in 5y might look like. Plus, again, make it clear where they are going--so you know when you pay $19.95 for 4 PGA tour players you will be using them in TGC 2024. I don't see any potential for monthly subscriptions it's just not required in any golf sim. With Flight Sim, that is not the case and I'm pretty sure MS will be doing their next version w/ realtime streaming graphics thru wide bandwidth. This is clearly what is needed in that domain, but as I say not so in the golf domain. So there is no real place for subscription that I can see for TGC or any other golf title.