Mlb has to realize that streaming on a dedicated network doesn't replace RSN and cable revenues. Don't they have to sell the package to Amazon Prime, ESPN, or Netflix in their packages?
Another factor I wonder about is what sort of ads will run. That is, my wife and I watch Caps games through the Monumental app because YouTube TV doesn't carry that channel. The ads we get are different from the ads people watching via a cable or similar provider get. We see far fewer different ads and they tend to repeat the same two or three ad nauseam—for example, around Christmas and New Year's at every commercial break we knew we would see that software ad with the two female real estate agents in which one of them sits on what looks sort of like the Iron Throne made of real estate signs, which in turn would immediately be followed by a PenFed ad. Last fall, we were seeing a Virginia Lottery Pink Panther ad at every commercial break (sometimes twice within the same commercial).
Because of that, I can't help but wonder what the Nats will experience in this regard. I don't really know how the logistics of advertising work, but I gather that a sponsor buys ad time not just for a specific program but also for a specific way of delivering that program. The lower variety of ads we experience through the Monumental app makes me think they must be receiving less advertising revenue for the standalone streaming option than they are for more traditional means. (While generally I don't care much about commercials, the lower revenue is an indirect concern because it tends to make me think pricing will increase somewhere else to make up for it—either an increase in the subscription cost, for those who pay, or an increase in season-ticket pricing in the Caps example where the subscription is included with your tickets. Also, while I don't always pay a lot of attention to the commercials, you can't help but noticing, and getting tired of it, when you see the same annoying ad something like 15 times during a single game broadcast.)