The article specifically mentions that it's business travelers that aren't flying (and let us assume sufficient fact-checking was done - it's the Associated Press, not a blog). So, apart from high-mileage leisure travelers (an area where FT is way, way over-represented compared to the general population), there will be fewer high-mileage travelers, and so fewer elites from BIS flying.

Fewer elites on fewer flights and smaller aircraft doesn't mean there won't be ample competition for upgrades and awards, however. (Yet I am over 80% successful as a mere gold YTD.)