Difficulty, in itself, shouldn't ever be looked at as an issue.  If anything, it should be considered a benefit because the additional hashing power makes for a stronger network and a more secure system.

What is happening with ASICs currently has happened before, but in a different way.  When CPU mining changed to GPU mining, those still mining on CPUs were getting smaller slices of the pie, but had the option at the time to go out and purchase at least reasonably available hardware to compete with others making the same change.  Something similar happened with FPGUs, but at a smaller scale because of the relative cost of FPGAs, the only major gain was in the reduced power utilization in most cases, and the looming of ASICs not long afterwards.

With ASICs, it is true that the same shift is occurring again, but this is the first major shift where miners are not able to reasonably acquire the hardware to continue to 'keep up'.  I think it will be interesting to continue to watch this latest shift play out.  I've seen on other threads how ASICs that are being purchased as recently as today have very little possibility of paying themselves off at current prices, but without a crystal ball, no one can say that with certainty either.  In early 2012 when BTC were at $4 - $5, ROI looked very different for GPUs at that time as well, fast-forward to current BTC prices and it looks quite a bit different.  The "when to shut down GPUs" conversations have been taking place since July/Aug or 2012, if not before that, and GPUs are still mostly profitable today, although maybe not for much longer.  Only time will tell.

For the record, I do not own any ASIC hardware, do not have any or order or pre-order, and do own a decently sized GPU farm, but this isn't a poor-me post.  It just is what it is.  If there was a reasonably-priced, fully-trusted vendor selling ASICs, would I order some today?   Maybe, but kudos all the same to those who took the right risk with Avalon and ASICMiner and have been rewarded for choosing well.