Pat, all magazines do extensive demographic profiling of their readership, subscribers and trade loyalists.
No one has ever done a specific study of (potential) architecture readers or followers. However, I have seen the results of two major national golf publications asking about specific reader preferences for articles, with instruction usually in the top 60%, followed by PGA Tour news (circa 30%) and architecture well behind fashion and travel in the 2-3% region.
These numbers are borne out by data from book publishers on sales of architecture-related books, where sales of 6,000-10,000 copies are considered excellent per volume, numbers that would prove disastrous for instructional or golf biography books.
This is part of my contention all along that architecture is an extremely narrow niche of the golf consumer market.
There are already too many national, and regional magazines, with not enough readers, with great turnover all of the time in their existence, plus extensive competition among them for advertisers. Such competition is likely to get worse given industry consolidation.
I feel lucky that Golfweek allows the space it does to the subject and is able to meet that niche for its readers. Ask yourself how much space in the other magazines is devoted to the subject. You might think the market is under-served, but you'd be in a small minority.
I wouldn't venture a guess as which advertisers to appeal to, but there is certainly no possibility for such a magazine unless it is heavily subsidized by its readers. The more photography, the more expensive the production and distribution costs.