Being a reformed cruisaholic, and vet of dozens of cruises, I have seen the transition happen s-l-o-w-l-y. Today, it largely depends on the cruise line. Disney is the worst for smokers, Carnival among the best. i.e. Carnival tends to draw a younger crowd of party-goers - the type that tend to smoke. Carnival DID try a smoke-free ship, but eventually discontinued it; because the casino business was a fraction of their other ships, as was alcohol sales. Beleive it or not, alcohol sales can make the difference between a cruise being profitable or not (not on Disney, they get it all in the cruise fare, which is 2 times higher than others). Celebrity Cruises & Norwegian are also more tolerant than most. European cruise lines are completely different - they would be out-of-business if they were oppresive toward smokers. I don't think e-cigs will be a problem on ships - they need your business ...just be cool about it, don't flaunt, & stay clear of Disney.
Actually, I think Celebrity changed their smoking policies of late. They're one of the more restrictive - no smoking in rooms or on balconies and even the casino. Here's a good write-up on the smoking policies at cruise critic.
Cruise Line Smoking Policies - Cruises - Cruise Critic
Carnival is certainly one of the least restrictive although I've heard of a few ships adopting a more restrictive 'test' model. Oddly enough, on those ships, you can't even smoke in the Cigar rooms.
