I don't see hybrids lasting. charging times are getting faster over time, why add all of the complexity and maintenance issues of an engine to an otherwise electric car?
A small engine just used to generate electricity can be cheap and effect without adding much in weight or complexity. It expands the market for car makers and basically gives good selling points for consumers.
Like we are talking about 2 cylinder engines that run at a specific RPM to produce the optimal level to charge up the batteries. Really isn't complex at all.
I feel like it would be a selling point like AWD or a third row seat. It would probably be a $2-3k option that dealers would push people to get.
People that park on the street or like to take road trip or just don't have the time to stop to charge would probably opt for it. I could see it an easy selling point to families or housewives. All a salesmen would have to say is "what if you are running errands around town and forgot to charge when you notice you don't have enough range to pick your kids up in time. You want to stop and wait to charge the car or just stop at the gas station and get a couple gallons of gas?"
Dealers really dictate what options people get with cars. Like in NE Ohio, Audi dealers don't stock non-quattro cars, they just sit on the lot. It also hurts resale value if try to sell a FWD Audi in an area that gets snow. If something is initially a popular option, it probably wouldn't go away in the future because of how dealers stock their lots and the waiting period for special orders.