re: potential growth/out-of-sight-out-of-mind, we won't know until the linear part is announced. ESPN is apparently close, FOX is apparently a maybe. Think everyone agrees there's not going to be any major fees for whatever games they get and it's already been said it'll be much less total number of games than what they have now. It'll just be about having 'some' presence on TV. If it's just a handful of random games and MLS Cup, not great.
Otherwise everything is with Apple. No one who isn't already a fan is going to pay specifically to watch MLS. A lot of current MLS fans won't pay either. STH get it for free so it really boils down to being something for current fans. Not a grow-the-league deal.
A lot of the spin in other places goes too far in each direction, naturally. The one that people aren't getting is that you have x-amount of people that watch MLS on TV now, and everyone spinning positive is acting like 100% of those people will transfer over to Apple, buy the MLS package and PAY to watch MLS. It doesn't work like that.
Within it not working like that is how many people think of things. Even though they're paying for cable or youtubeTV, etc., they don't view it as paying to watch MLS.
(note: another thing people don't get is that not every MLS teams local deal is with a RSN. Plenty are with local ABC/NBC/FOX/CW/Ind. affiliates, that's OTA.)
So they watch their local MLS team on "FOX" (local FOX affiliate), watch them when they play on ABC and FOX (national games), ESPN/2 and FS1. They "think" they watch their local MLS team 'for free'. Now tell them they have to PAY to watch their local MLS team. That'll be more of an issue/lost fans than people are realizing.
Plus, just because 58% of the MLS fan base is Gen-Z/Millennials doesn't mean that all 58% are cord-cutters or that anywhere near 100% are going to be willing to pay for a product they currently get included as part of their streaming service(s) of choice, or of course sat/cable because plenty of that 58% still watches things via sat/cable provider.