Are there any trans main characters in a broadcast TV series? Not Netflix original, not Hulu, not satellite or cable, but ABC/NBC/CBS/Fox free-to-air broadcast TV. I can't think of any off the top of my head, and I think that comes down to the demographic targeted by broadcast TV: People fifty or older.
https://www.marketingcharts.com/television/tv-audiences-and-...
> According to the analysis of audiences of 5 networks measured using Nielsen’s Digital Content Ratings in September 2018, 59% of live TV viewers ages 13 and older were in the 55+ group, compared to just 5% who were aged 13-24. The median age of a live TV viewer worked out to 56. MarketingCharts’ own research – US Media Audience Demographics – has found that weekly broadcast TV viewers are skewing older over time, and cable TV viewers also have a growing skew towards older adults.
Also, let's look at the other broadcast medium, radio:
https://www.marketingcharts.com/demographics-and-audiences/m...
> While the age distribution of network radio listeners skews towards the 45+ demographic, a large share of Americans of all ages listen to network radio. The study also points out that listeners are spread across the US and tend to represent an attractive group in terms of their income and education levels.
Also graying, but more slowly. And, yes, it's a trend:
https://www.westwoodone.com/2015/06/24/this-just-in-new-data...
(Graph on the bottom shows median age of radio listeners increasing.)
My point is this: Shows made for broadcast media are not going to change because the people making those shows know their demographic and aren't going to shed viewers by doing things their audience considers controversial. Viewership numbers are low enough already. Broadcast media is in a death spiral and whatever stereotypes, representation, and lack of representation it currently has is what it's going to have from now until it goes dark.