Will we be able to obtain all starters in this game like we could in PLA? Honestly, one of the absolute best features about PLA was that you could obtain all Pokemon in the game.

The artificial scarcity of starters that has existed since Gen 3 is honestly out-of-date at this point. Every single romhack you see these days finds a way to make all starters obtainable, yet still extremely rare and hard to find, which is exactly how it should be.

If the other starters can only be obtained via trade once you have started your journey (and mons like Electabuzz and Dusclops need to be traded to evolve again), I think its safe to say at this point that Game Freak expects you to buy both games to catch all the Pokemon. This and the fact that they literally release an official double pack, I think it's fairly safe to assume that the 'two version of the same game' thing has always been a con to get people to buy the same game twice. They've already proven that they don't need to do it, so SV is going to be the ultimate test. I hope I get proven wrong.