I hope this finally works out. I remember almost exactly ten years ago I got excited about one of these proposed cancer cures, tried to talk about it at lunch with my coworkers, and they laughed at me for believing.
Real in vivo genetic engineering isn't going away and will indeed be a powerful tool to face cancer. Any particular effort is doubtful because this is a journey measured in decades. It is not the same story as any one particular wonder drug fizzling out to nothing, it is a class of tools that is maturing into the realm of early therapeutic deployment.
I'm pretty optimistic. I think it's a threshold question where we need a number of basic technologies to all get over certain bars before the floodgates start to open.
Over the past 1-2 decades there has been unbelievable progress at the basic technology level but most people are unimpressed because they haven't translated yet due to not individually being sufficient to cause an explosion of progress. IMO, we're starting to see it finally as so many different technologies have gotten so cheap, fast, and good.