How long will SNG's stay REALLY profitable?

[stanzee]

This has probably been spoken about before, but how long is it before SNG's start become a lot tougher even at the lower limits.

I've heard posters mention in the past that on the 109's and the 215's that it is already really tough to get any sort of edge as most people know how to play the bubble near perfectly, and wont make any really stupid moves before hand for example with top pair no kicker. My worry is that sooner or later all the donks playing the 11's to 55's will wake up and smell the coffee and learn how easy SNG's really are if they could just discipline themselves. Then i'll have to go back to learning NL cash games [img]/images/graemlins/frown.gif[/img].

Does anyone think that SNG's will still be as easy as they are now in 5 years time, or even 3 years? I really hope they will be, but not sure.