If these delis are disappearing, I propose that it’s simply a case of supply and demand.
While there may be a goodly number of persons around that enjoy this food (and I count myself in their number), that number isn’t enough to keep many delis going (and certainly not enough to keep real Kosher delis in business, where expenses are higher by virtue of the cost of compliance with dietary laws, and where cheesecake and pastrami cannot coexist). If the customer count were larger, you’d see more delis flurishing. Simple as that. I’m afraid that Jewish deli-style food isn’t fashionable enough to compel the same level of interest as an Emeril or Flay. Times change; tastes change. Pacific rim its not.