It's not enough to keep abreast of SE developments; you also need to keep abreast of your niche, your audience's tastes, and your rivals' activities.
With those variables - and a few more besides - it would be an arrogant and foolhardy webmaster or SEO who could promise a few months, let alone years, decades and lifetimes ahead.
But I take your point; there is less mystery about SEO these days. Most of those who have kept abreast AND got penalties would be less surprised than the white-text-on-white-pages folk of 1999. These days, 'black hat' is a career choice, an accepted risk, an increasingly known risk - not a matter of luck, sneakiness and bad advice.
On the other hand, we now live in a time of constant change, in all areas of web site management - time will come when even the Google Bashers will look back on the 'Google Days' as a time of stability and openness.
And that uncertainty will probably get worse. No-one predicted the dominance of Google, let alone Adsense / Adwords. No one predicted the power of YouTube and its effects on everyone else - and no-one knows how it will be monetised. No-one predicted that 'web 2.0' (dread term) would come to mean yourface, spacebook or whatever superficial twaddle it is that dominates teenage thought ...
Bored enough yet? The future is a dangerous place. Don't go there!