Not any time soon. The market would crash before it even hit $50. Maybe someday in the very distant future when mining is no longer possible. Perhaps 2-5 years down the road.
Mining should be possible until 2041ish when all coins have been mined...unless i'm missing something
2144 ish - and then transaction fee's will cover it (well long before then, but there will still be a block reward over half a bitcoin until 2144ish IIRC)