I am VERY curious as to the whys.
I don't think that this really is a question.
The response to either Shafer_5 or the patches was underwhelming, to say the least.
Yes, some new people have been attracted, no doubt, but most of the sales are coming from oldtime fans.
For BtS, he was only the co-designer and as we've heared was responsible for some of the least appreciated features therein (espionage).Shafer had his successes too; Final Frontier mod for Civ IV and Civ IV BTS. CiV was a major disappointment though.
But to anyone looking at Shafer's resume, CiV is a colossal success, not failure.
Anybody in the gaming industry knows that Shafer_5 sold well since being based on the fans' experiences with Civilization 4.
Take away the brand name and experience 75% less sales.
Back to topic:
Personally, I expect now two things to happen.
First, there will be some more DLC to drain the last bit of money out of the game and that's it.
Second, I expect them to already be working on Civ6 behind the scenes. Well, maybe not really working, but analyzing what went wrong with Shafer_5 and how to avoid such a bad echo from the fans.
Shafer_5 may have sold well in absolute figures, but I am pretty sure that it missed the expected figures in a considerable way.
The absolute sales figures are a heritage of previous Civ versions, as the longtime fans couldn't wait for the new version.
And then, from day one on, the game was under fire, because of the very well known reasons. For sure it didn't get much positive mouth-of-mouth advertising. Not in a large scale.
I think, Shafer_5 has been buried.
We will have to wait for two to three years and then we'll see what they present us as Civilization VI. And if not them, sooner or later another company will take care for the fans of the genre.