Economically: Many channels will die, which would lower production costs, which in a competitive market lowers consumer costs.
More importantly, channels will actually need to fight for consumers. Which means they are not going to soft ball ultra cheap reality TV that most of their core demographic hate. cough syfy
Really, it's just a question of what they get from all their channels (X + Y + ...). If Y = 0billion and X = 10billion that's the same as Y=1billion and X = 9billion.
PS: Ok, their might be some accounting magic so it's useful for channel Y not to be profitable.
PS: Cheap TV can be compelling. Personally I really liked the primitive technology youtube channel which has 788,764 subscribers and is really cheap to produce 1 guy without any spoken lines. Twitch can also be extremely compelling. However, that's not paying subscribers.
That means that cable operators are sort of duty-bound to offer local stations. I will bet that those local stations are much less likely to be in your list of 5.
So what's mainly driving up your cost is local stations charging for carrying them. You'll see the odd game of chicken between local stations and cable operators when the local stations want to raise prices.
That is, I've already proven to Xfinity that I'm willing to pay my monthly cable bill for those 5 channels, so if they offer them a la carte, those 5 will cost about what my monthly cable bill costs.