Now that Gen 3 is about to arrive...
Niantic seems to have enabled everyone to gather and power up all first and second generation Pokémon, first the big city dwellers, then the rest of us by events and then by raids. So virtually everyone will have good attackers and defenders of just about any type. This was clearly different a year ago.
So when the third generation comes, existing pools of attackers and defenders will be able to handle everything. The newcomers would add numbers but not capabilities.
So, things could get a little boring unless something like Abilities are introduced. I have no experience with the original games, so what to expect? Are they tied to a Pokémon you find, or are they picked up somewhere? How would existing ones get them? Are you looking forward to this?
Answers
Here's a list of abilities:
https://pokemondb.net/ability
I scanned the list and identified only a handful that would be applicable in PoGo, since most of them rely on status (like confused or poisoned) or effects (like weather). I don't see Niantic implementing them unless there is a total overhaul of the battle mechanics.
Example:
Dragonite's primary ability is Inner Focus, which prevents it from flinching. But no moves in PoGo can cause a mon to flinch in the first place. With a battle system that relies solely on tapping and swiping to dodge, flinching and losing a turn simply isn't a thing. Its hidden ability (and the one main game players really want) is Multiscale, which reduces damage when Dragonite's HP is full. But in PoGo, that would only help until the defender fired its first move. Without status moves (like Roost) to restore HP, it's pretty useless in PoGo, too.
Having said all of that, I would much rather Niantic implement some sort of modified abilities than introduce natures in PoGo. Because natures can raise or lower certain stats. For example, a Bold nature raises defense by 10% while it lowers attack by 10%. If they assigned random natures to our existing Pokemon, and my 100% Dragonite got that nature instead of Adamant (which raises attack by 10%), I would most likely have a meltdown right then and there.