I doubt you'd be required to subscribe to YTTV.If Google gets it, will they require you to sub to YouTube TV to get NFL ST? I mean it's cheaper than DTV, but I have no intentions of leaving DTV, not for a while, if they decide to make you sub that's BS, I get you have to sub to Prime(which is like $16.19 a month for me, big deal), & Apple TV+($4.99 a month, big deal), I'm not paying for a service I don't want to use, but I guess if I want the Ticket I'm gonna have to, but if the NFL wants to get more subs they better make it so you're not required to pay for additional services, I get you needed DTV to get the ST, but I just find it to be BS if I have to sub to YTTV, as for pricing, I hope it's not above the current Max price, which is close to $400, I have it free this year, but am willing to pay the $400 for ST, and hope for payment plans like with DTV.
I'd think it more likely be an introductory offer, sub to NFST and you get YTTV for free or significantly discounted for the duration of the season.
The other services, the prereq makes more sense, but could take a similar approach there too.
A lot of value getting people into the ecosystem.