Come on, you guys - you're well on your way to turning into that most scorned of wine drinkers - the "Wine Snob". Can you hear yourself: "What DOES a true cab taste like anymore?" I can almost hear your "sniff" and "tsk, tsk" afterwards. Pretty soon I'll read something like, "Back in 19__, when I was a lot younger, we knew a thing or two about wine, and these newer wineries just don't make 'em like they used to..." The country bumpkins and hicks among us don't relate very well to those attitudes about wine - so you'll have to lay off the Napa Valley references - Missouri River Valley and Finger Lakes references are ok, though...
But seriously, I can think of several reasons why this question should not even arise here:
1) We're home winemakers - we make our own because we don't want to buy commercially-made products (for various reasons, including price but also taste)
2) What commercial wineries produce for retail should not be our concern since we are not trying to "compete" with commercial products, but to replace with those wines something different and hopefully better (how many times has it been said on this forum that you should experiment with the flavors/additives/modifications that you personally like, rather than what is typical or recommended?)
3) Our perception of a "Real" cab (if we could even agree on that point) is not what was 20 years ago, and that was not the same as 40 years ago, because products and markets change over time. I think we can all agree that the cabernet sauvignon grape varietal is the same genetically, but inevitably grown under different conditions in different locations as various factors cause that to change (land prices, environment, agricultural methods/chemicals/organics, etc.). from year to year let alone decade to decade.
4) BUT the biggest point is the fact that California wineries all but invented the concept of a single varietal wine some 60-90 years ago, so before then, almost no consumers knew or cared what varietals were in the bottle - they just knew if it was a good blend of wine or not. Comparing wines was less precise and different wines were simply not as comparable in a tasting setting, but that was why vintage years mattered and winemakers' knowledge and experience with HIS vineyards (of different varietals) was critical. Nowadays, wineries just buy grapes from any old place, ferment whatever crap they got in bulk at a cheap price, bottle it and sell it - the "Backstories" and special techniques employed/described with great solemnity (modern methods of testing, filtering, "organic growing methods", etc.) are just melodramatic propaganda for the purposes of marketing/selling swill with a high price, in my very humble opinion.
Do not lament that the flavor of a wine you like has changed and can't seem to be re-created - that is part of the allure and the unattainable ideal that makes wine so spectacular and engrossing. I recall a wine I had some 15-17 years ago when I was still in my teens that was so silky and smooth, it was like nothing I had ever drank before or have since - I still remember it as the perfect texture of any food or drink, but have not come close to tasting it again. Even though I doubt I will ever find that "perfection in a bottle" again (I think it was a Barolo), I'm still hunting for that experience again...