It will be interesting to see if the new MLS model catches on. I'm not a big MLS fan but I wanted to check in on the Sounders' home opener but it's only available through that new Apple TV subscription. As a casual (at best) MLS fan, I'm obviously not going to pay $15/month for the MLS package on Apple TV and some of the bigger games are on Fox anyway. So it kind of splits the fans into two groups -- the serious ones who can afford it are going to pony up the monthly fee without complaint. The casual ones are simply not going to watch, but the idea (I think) is that they will catch the occasional national broadcast and get interested enough to eventually pay the monthly fee.
My feeling is that the subscription numbers for the MLS are going to be pretty brutal and that they would be better off giving all of their games away for free to try and build a bigger audience.
I can't imagine an MLB market like Milwaukee will be much better. I know we've run this math before, but let's be generous and say that 50,000 people in the Brewers' blackout zone will subscribe to get all Brewers games and pay $20/month for 6 months of the season. That's a measly $6 million in revenue. The actual number would likely be half of that, especially since you're probably going have discounts and give it away for free to all of your season ticket holders. IMO there's no point in even offering a subscription option if they can't get at least $10 million/year in subscription revenue. Anything less than that and they are better off making it free, collecting the ad revenue, and calling it an investment in growing the popularity of the franchise.