Casual soccer mom players do not know what updates are to things like this really and wont be coming back, this isn't like expansions to PC MMOs, those people tried it, was buggy and stopped playing it because of that. First impressions with some players are damning especially like I said if they aren't your standard gamer who is fine to basically beta test a buggy mess.

You mean how many pokestops there are? XD I don't know where you live but I like in a rural area and there aren't very many stops and not many great pokemon spawn here. 

Oh... it might have been in reference to the new tracking system which is being beta tested in small areas in the states, will actually show you a picture of the pokestop that the pokemon is closest to in the tracking window... where it just shows a patch of grass right now.

Oh i see. Im still very unfamiliar with how smartphone gamers reacts. 

I don't see it as declining, more like potential when the game updates. To be honest, that's the only why i've stopped. 5 days in a row hunting is too much, but if we were to add new features, more people will come back.

Ohh it isn't finished yet? That explains why every friggin pokemon is just in grass :P

Can't wait for shinies to be implemented.

So only 20 people are playing it right now? That's what I call a decline!

Yeah it should have like a nearby icon and the picture should be of a pokestop it is closest to where it has spawned, there will still be ones away from Pokestops which just show grass, but I think they should mostly give at least a sort of idea of where you need to walk towards.

What it should look like

Video I lifted that image from https://www.youtube.com/watch?v=8AeBV6SShYI

Updating an app is second nature to a mobile user, they just come from the store app, and by default these are done automatically. The main decline, I believe, are people just getting bored with it, be it the exponential progression or increased capture difficulty as you level up.