>just over 50%
k
(I feel like the glib single-character response stands on its own, but more verbosely: yeah, the trend isn't good, but a) there's no reason to assume it's linear, "fair-weather believers" is a thing, and b) I'm not a TIOBE follower, but let's say java use was 70% 20 years ago, and down to just over 50% today. Is "obsolete" the word you'd use?)
Yes, I stand by my words. If you read them again, you'll see you are arguing with something I didn't say.
If 29% of religious people have left the church (50/70=71% still attend church)... then that is a major shift. It would be foolish to continue with previous assumptions about the role of churches going forward without taking into account how religious people are changing their behaviors.
So what if, in order to accommodate the changing role of the church in America, you prevent the other minority religions and minority communities from ever having their centers grow in the same way churches were able to?