I don't think we'll see the evolutions of the starters yet, to be honest.
Because of the limited information we have, we know next to nothing about what we don't know, to put it confusingly. We don't know for certain if, say, Noivern has an evolution or a pre-evolution. We'd like to find out, but we'd also stay content if we don't get to know yet. Likewise with Mega Evolutions. We don't know what Pokémon will get them, but we'd like to find out. We're more interested in finding out if there is more to be known, rather than specifically what it is.
As for the starter evolutions, however, we know they exist. They will be revealed some day, you will encounter them during game play. They are very significant to gameplay. But, we don't know anything else about them. We want to see what we know exists, compared to the hypothetical Noivern family which might not. We have speculated a LOT about this, lots of people are asking themselves the same questions, we know there is an answer, but we haven't been told yet.
We tend to wish more for confirmation (or disconfirmation) of our theories, we want to know if our speculations are true or not. We want answers to our questions, more than we want new, unrelated info. Sure, it would be neat with the reveal of this generation's equivalent of Snorunt or Carnivine, but it would be a lot more satisfactory hearing about this generation's equivalent of Charizard.
Do GameFreak think in the same ways, though? Hardly. They want us to stay tuned to hear the answers we crave. Meanwhile, they keep feeding us teasers, giving us more questions we want to be answered the next time. For full satisfaction, we have to buy the game. I don't expect the starter evolutions to be revealed, as much as I expect to hear about this generation's equivalent of Snorunt or Carnivine.
