Once the mining doesn't produce a lot of coins anymore that is quite a bit of growth for all other coins.
Are you accounting for the fact that most of the miners would eventually move onto the next best thing (some alternative and profitable implementation of crypto-currency? Wouldn't all your bitcoins be lost then? Look, contrary to a popular believe in the GOLD 2.0 era, the pump and dump schemes (the drivers of USD/BTC exchange rates today) don't create deflation in BTC... The deflation in a BTC-based economy can only be created through increases in BTC spending, not through BTC trading. How many miners do you know who are spending their bitcoins like there's no tomorrow? Hoarding still seems to be the popular choice today.
Miners will still be able to gain money with transaction fees, but it's not new money.
But yes, it's possible that a better crypto-currency takes Bitcoins place and all BTC will be worthless then (it's not the miners who decide this though).