Won't the law of supply and demand ensure that mining remains profitable (if just barely)?  This is because, if difficulty rises disproportionately to price, so that mining becomes unprofitable for some players, then those players will stop mining, causing difficulty to fall to the point where it is profitable again.

In fact, this has happened already before, see for example http://i.imgur.com/rMrdY.png which is from http://forum.bitcoin.org/?topic=7427.0.  The price leveled off in mid-February, but difficulty kept rising, so by mid-March it was above 100,000x the BTC price in USD.  At that point mining was probably unprofitable for many players, and indeed, mining activity fell soon afterwards, to the point where it was less than 100,000x the price again.

This month, mining speed and difficulty has been catching up to the recent price bubble (where it went up to 30 in early June), but now (just in the last few days) mining activity is leveling off in response to the decreased profitability - as can be seen in this chart:  http://bitcoin.sipa.be/speed-lin-2k.png.  If the price doesn't go up soon, then before long the difficulty will fall, and mining will become more profitable again.

Bottom line is, don't worry about it - the invisible hand of the market will take care of the problem.