Well there is a physical limit, which when we reach an atomic level, for with processors, at which we can't make stuff smaller anymore. And other than that we see an obvious trend towards some particular phone width, for example. And it's not like phones are getting twice as thin every year, but they're slowly approaching a limit.

So yes, you might be able to play the game indefinitely, but I doubt anyone will care about those extra picometers a phone managed to shave of.

I don't believe it's possible to slightly decrease battery life indefinitely.

Also, there is a limit to thinness. Maybe the rest of the phone could be hidden in an alternate universe and the only thing that protrudes in to our realm is the direct visual cortex stimulator.

We'll see.