Where this spells trouble is aged shows grow more costly by the season. Station 19 spawned from Grey's 5 seasons ago, and incidentally is only two hundredths off in ratings. As-is, Station 19 is more cost effective as its cast's salaries are likely marginal compared to Grey's Ellen Pompeo. The same can be said with NCIS and NCIS: Hawaii, a newer, cost effective spinoff. Grey's and NCIS are not in danger by any means, but no longer hold the "Certain Renewal" tag they held for years.
Elsewhere, some bright spots have emerged among the onset erosion. The Chicago-Verse is down year to year but strong at the top of the chart, and Law & Order: SVU, a middling show in recent years, experienced a nice bounceback nestled in a suitable timeslot. NBC also managed to launch the first sturdy freshman drama with La Brea, which concluded its season this week. ABC has been pummeled to a pulp overall this season, but The Good Doctor is hanging strong, and The Rookie stood guard in the network's garbage timeslot and held steady as its weak lead-in deflated.
CBS may have procedural spawn running rampant, but 2021 holds more energy and it shows in the ratings. Almost all the spawn of the parent franchises succeeded this season, save for CSI: Vegas. SWAT, formerly one of the weakest procedurals, experienced a renaissance after relocating to Friday evening. As for CW, do they even care about the Nielsens? Their strong point is The Flash and Walker delivered strong as usual, but All American has stood strong and is now one of the leading players.