I mean, I like to believe we’ll get close to that eventually, but even as an extremely dedicated Nintendo fan myself, I can’t say I’m that confident and optimistic that that will actually happen as you describe it.
For one, I don’t think Nintendo can sustain throwing every past game from every past system onto a subscription service; either they’re going to have to continue to introduce more and more subscription tiers (which will get very messy—and very expensive), or they’ll have to come up with some other solution for systems with higher value (and bigger sized) games like GCN, Wii, and 3DS such as going with a more Virtual Console-like distribution method rather than subscription…but that would mean we’ll be less likely to see some more niche games (I’d especially worry about stuff like WiiWare or 3DS eShop games—and honestly I even worry about DSiWare even if we get DS NSO).
And then you have to consider that even if Nintendo did put all of those on NSO, many third-party games would still be missing due to the respective third parties not cooperating. Even if you’re confident that Nintendo will get all of their games on NSO in time, there’s no way to guarantee that we’ll see games like Yo-kai Watch and The Denpa Men on there, too.