It's rare that MARTA has changed the realtime train API. And this is definitely the biggest change I've seen in the decade I've been using it. A longstanding complaint I have gotten while maintaining marta.io is that it only includes active trips, or moving trains and their destination. On Friday I noticed that their new train API endpoint includes future, scheduled trips. I added some quick styling for them (faded pills, calendar icons), and am excited to give it a whirl next week!
They have changed the station signs as well! They added little "signal" icons on the longstanding "realtime" entries, the non-scheduled ones. So if it's an undecorated entry on the station signs, my impression now is that it's a scheduled/future trip. I was excited that they made the same data available in the API!
I chose to de-emphasize the newly added data (which is valuable, but imo less valuable than the longstanding data if it's present). So I'm fading things out and marking scheduled entries, rather than changing the data that has always existed.