Well it's already been said - Bubble, oil, budder etc. is already pretty damn strong being in the 50%+ range. It simply won't get much stronger than that (unless we start talking different, artificial cannabinoids) so there is a limit.
People have been taking huge oil hits - doing gauntlets emptying bowl upon bowl into their lungs etc...
With all this talk about the increased potency of weed, and the 'killer' strain called 'skunk', I still haven't smoked any weed as good as that I smoked back in the mid 80s. I'm still looking for a strain that compares. So far no luck.
I am not so much talking about media hype - but the grower's (and buyer's) desire for something stronger. I just don't buy that the 70s and 80s strains were any better (stronger), maybe different. Either way - its just an interesting topic of discussion. What if we only found out that we had found the "perfect" strain - when we were all addicted! Just a topic of conversation. There have been other drug communities that have found themselves in that predicament.