That’s not happening. That would be a replacement for out of market MLB, NHL, and NBA packages. You could get pregame and postgame shows, but not the actual game.
Right. Sinclair only has in-market broadcast and streaming rights, and obviously only for the teams covered by their specific channels, e.g. Bally Sports Midwest has the St. Louis Cardinals (MLB) and St. Louis Blues (NHL) games; Marquee Sports Network has only the Chicago Cubs (MLB) games.
So if you sign up for this proposed $23/mo streaming service, you're only going to get the games that they're cleared to carry in your zip code. As you say, you might get their out-of-market pregame and postgame shows, or other news/talk/highlight shows featuring out-of-market teams, but you're not going to get those out-of-market teams' actual games. For that, you must subscribe to MLB Extra Innings/MLB.tv, or to NBA League Pass, or to ESPN+ (for out-of-market MLS and, starting next season, NHL games).
I was predicting that this Bally streaming service would come to market for $19.99 or less per month. So $23 sounds a bit high to me. But I can see it making sense for some fans looking to cut their TV expenses if they really don't care about much on cable TV other than their local team(s). The only streaming cable TV package right now that features RSNs is AT&T TV's Choice package, which is $85/mo. And that's pretty close to the incremental amount you'd pay to add Comcast's standard cable TV package that includes RSNs to their standalone broadband service. So let's assume $85/mo is the standard price for a cable channel package that includes your Bally Sports RSN.
If you could use an OTA antenna to reliably pull in your major local broadcast stations (ABC, CBS, NBC, Fox, etc.) for free, then you might replace your $85/mo cable TV package with Bally's $23/mo service, saving you $62 a month! Not bad. If you still needed a major national sports channel, you could pick up either Sling Orange (ESPN/2/3, TBS, TNT) or Sling Blue (FS1, USA, NFL Network, TBS, TNT) for $35/mo. If you wanted both that's $50/mo, which, when added to Bally's $23/mo, puts you at $73 total, in which case you may as well stick with a regular full cable TV package and not fool with an antenna and multiple apps.