It has been said before that iOS 13 might not support the iPhone SE due to its screen size, but since the new iPod touch has the same screen size and will surely support iOS 13, that shouldn't be an issue.
Right, but since a 4" screen is no longer a limiting factor, we're back to the A9 processor being the possible cutoff, which also ends support for the 6S.
I hate this short sighted attitude. There are TONS of reasons to have a dedicated iPod. Not everyone wants to risk their $1500 phone in a sweat and metal filled gym. Not everyone wants to use wireless. Not everyone wants to store their music on their phone and kill the battery during their workout. Not everyone wants to be interrupted by a phone call during their workout.
So then why did they discontinue the SE? All they had to do was put in an A10 and they'd have a cellular iPod Touch. I don't believe for a minute there's a larger market for the iPod Touch than for the SE.
As for the reasons you list, risking the $1500 phone is certainly acceptable. But then an Apple Watch would do the same job for about the same money. As for not using wireless, that's a moot point with respect to the iPhone -- since all iPhones have a Lightning connector for attaching Lightning headphones, or an adapter. What's particularly boggling about this is that Apple wants its customers to subscribe to Apple Music -- this device encourages the continued use of downloading music. Regardless, I listen to streamed Podcasts at the gym over BT headphones, and I have never even come close to "killing" my battery during even the longest workouts. And even if yours does, there's always a dedicated Apple battery case you could slap on for the gym. And ultimately, if someone doesn't want to be interrupted by a call during their workout, merely turning on Airplane mode will accomplish that, or set "Do Not Disturb". All of these points are better options than a dedicated and outdated iPod Touch.