In my opinion, quality "pocket nines" have sufficiently negated the J-frame type guns and I think that the plethora of quality service/ duty semi autos did the same for service revolvers a LONG time ago.
The problem with "pocket nines" is that there is no free lunch and the reduction in size comes at a certain cost. Nearly all the "pocket nines" on the market use a locked-breech design of some sort with the most common being the Browning-type tilting barrel. For a given action type and size of cartridge, there is a certain amount of space necessary for the gun to work. Because of this, the way in which semi-autos in service cartridges like 9mm, .357 Sig, .40 S&W, and .45 ACP are miniaturized is to essentially shorten the barrel/slide assembly and/or the grip.
Shortening those dimensions creates a number of potential reliability problems. A tilting barrel semi-auto keeps its slide closed long enough to allow gas pressure to drop to a safe level through the inertia of the slide, which is directly proportional to its mass, and the tension of the recoil spring. When you reduce the mass, and thus the inertia, of the slide, the weight of the recoil spring becomes much more critical to reliable function and it is more difficult to reach the proper balance that will keep the slide closed long enough without adversely affecting function.
Reducing the length of the grip also increases the chances of malfunction due to limp-wristing. In order for a semi-auto to work properly, the shooter must be able to provide a reasonably steady platform for the frame in order to make it more resistant to movement than the slide/barrel assembly. Shortening the grip makes it more difficult to keep the frame steady in two ways: the reduction in mass reduces the frame's inertia and thus makes it more susceptible to movement under recoil and the reduction in the length of the grip provides the shooter with less surface to hold on to thereby reducing the shooter's ability to prevent movement of the frame.
In contrast, a revolver's operation is dependent solely on the strength of the user to cycle the action. The only possible reduction in reliability due to shortening the barrel and/or grip of a revolver is the possibility of ammunition jumping crimp under recoil due to the increase in recoil that is unavoidable with reduction of weight. However, crimp-jumping is not particularly common and is most often encountered with extremely lightweight revolvers (usually made of exotic metals like scandium or titanium) firing heavy-recoiling ammunition (most often magnums of some sort) with cast or swaged lead bullets. Using a steel-frame revolver, lighter-recoiling ammunition, and/or jacketed bullets is typically sufficient to prevent crimp-jumping.
Now, if your "pocket nine" has been 100% reliable for you and you've tested it sufficiently to trust it under adverse circumstances such as a weak grip due to an injured or weak hand, that's great and I'm glad you've found something that works for you. However, just because a "pocket nine" works for you does not mean that it will work as well for everyone else and a snub revolver is simply more likely to work reliably for a wider variety of people than a subcompact 9mm is.
As for autos taking the place of a full-sized service revolver, again both platforms have distinct advantages and disadvantages. While a semi-auto may be the best weapon for the average cop or soldier who has received, hopefully, reasonably extensive training in the use of his/her weapon, the simplicity and neglect tolerance of a revolver could very well make it a better choice for a private person who's received little, if any, formal training.
Also, a revolver offers the ability to use much more powerful cartridges without the need to carry an overly large, heavy, and bulky gun. About the most powerful cartridge that is commonly available in a "service size" semi-auto is 10mm Auto, and even it suffers from somewhat limited selection and availability of both guns and ammunition. While semi-autos such as the Desert Eagle and Wildey chambered for more powerful cartridges are available, they are much larger and heavier and typically more expensive than a "service sized" revolver or semi-automatic. In contrast, I can carry my 4" S&W 629 with no more difficulty than I can my 1911 or CZ-75.
While the more common "service" semi-auto cartridges may be perfectly adequate for the average police officer, a person who is just as likely to face a four-legged threat as a two legged one or someone, like myself, who is most likely adversary is an extremely large individual may be better served by a more powerful, deeper penetrating cartridge.