Trading Isn't going to hurt more than help... but i get their fears as once you collect them all what is there? Gyms? I don't even touch a gym unless its getting close to my claiming time what with how quickly they get overthrown.
Every Pokemon game has an end, and until they add Trainer Battles theres a finite amount of Pokemon to collect and raise.
A decline will happen, its bound too, but if they fix their ***it'll happen slower.
Servers are great, they've made god progress there for sure, so its not like they're doing nothing and I'm not suggesting that, its just with every fix they seem to remove or break something else... all in time I suppose.
But to think its because of trackers? Nah, you created a Pokemon Tracking game and you've now removed the option for tracking, presumably to fix and return later, But still... you've removed half the reason the game exists.
I understand them not liking the Poketrackers but they were birthed out of the fact their own tracking system was broken and unfinished... if they fix and finish it the need for trackers will dwindle and fade.