Mine for transaction fee cause the fee would be really high if everyone starts using Bitcoins....
I can't wait to see where transaction fees will bring the block rewards to. IMO, I think we'll see larger payouts from transactions than the 50 BTC rewards of the old days ..not tomorrow, of course, but in good time. In fact, it wasn't long ago that I saw a 6-8 BTC bonus of transaction fees on a block solved by Slush's pool.
Very unlikely. Tx fees are likely to remain low. Then again the purpose of mining is to secure the network not get rich quick. As the value of BTC rises the nominal amount of BTC paid in fees per tx will decline.