A few thoughts from an outsider, regarding earlier posts in this thread.
1.) Although I've grown to enjoy WERS, I do question if we'll see a day where its HD-2 format takes over the main frequency/HD-1. That's with noticing the statement which pointed out the change in urban demographics. I also don't see WXRV as completely comparable to it. I see it on a fringe, with the other fringe being the internet alternative station (Indie617). The thing about non-commercial is that it is a fan service. Have K-Love go commercial, and let's see how fast it gets flipped to a variant of safe modern or classic pop music.
2.) Mix isn't going anywhere, unless for some reason it's moved to another frequency (which makes no sense). I don't know how it bills, so I'm only going off recent "pagent" ratings. It gets numbers, and I theorize that it makes for a decent female companion piece to WMJX. The discussion of Alternative is a moot point right now, as markets with Alt stations are showing low pagent numbers. They're still around in those markets, so I wonder how they also bill.
3.) Big 103, I don't see it as an attempt to be the old Mike-FM. My theory on Big 103 is that Audacy had WAAF, WKAF, and Mike-FM at different times. I theorize that they wanted a cheap station to operate, had a small gap in their portfolio where these specific songs test well (yet didn't fit into a "viable" full-time single format), thus put them together onto a "We Play Anything" station...without having to pay the rights fee to use the Jack-FM name.
My personal taste doesn't coincide with much of the Boston FM radio market anymore. I paid for the top of the line engine without the full interior comforts, so my truck doesn't have HD-Radio or SiriusXM. My wife's car has the latter, but I rarely drive it. These are my specific preferences. Modern radio seems to not support modern rock in large markets (due to numerous variables), which is my go for music genres. I don't mind Rap, but don't like Pop. Country is a large pass for me, personally. I can't fully listen to grown men who don't play sports, talk all day about it. If I'm that interested in a game, I talk with my friends and colleagues about it. And I rather listen to my truck engine run than any kind of political talk. I'm in the middle and can't stand the far rhetoric from both sides. I much rather download a Podcast and listen to that (uncensored) through my phone being Bluetooth connected to my truck radio. When using my radio with the kids I default to either WZLX, WBOS, or WHEB out of Portsmouth, New Hampshire, if I'm not listening to music from my phone. I also would use WGIR-FM, but recently their sound quality is muffled compared to sister-station WHEB. It's easy to notice, but for a 1:1 comparison, listen to both in the morning when The Morning Buzz is on both stations. The audio quality is superior on WHEB, which wasn't the case a year or two ago. They were on equal par with each other. Believe it or not, if I'm driving alone, not feeling the music on my phone or a Podcast, I find myself listening mostly to WBZ-AM or WGHM-AM out of Nashua, NH. That's just my personal preference.