I'm seeing a lot of no's here with regards to a product like this, but if I'm going to be honest, we may see a product like this in several years' time. I agree that it may seem like a waste of space, but considering Anker's efforts in making accessories for Apple products and the direction that I believe Apple is going in, they may end up making something quite like a wireless charging power bank.
Now, I recognize that I've made a bit of an odd claim here, but let me explain. It is my belief that Apple is, over the next few years, headed for an entirely wireless, entirely port-free iPhone. Over the past few generations of iPhone, they have made several decisions that point towards this as a potential long-term plan. First, they made AirDrop, a simple, fast, and completely wireless file transfer system. Next, with the iPhone 7, they removed the headphone jack, with the justification that it would make waterproofing easier. At the same time, they released AirPods, a wireless version of their ubiquitous earphones, with a proprietary W1 bluetooth chip to make pairing the headphones (as well as a few third-party options such as powerbeats) extremely easy. Now, with the iPhone 8 and X, they have introduced wireless charging using the most popular current standard, Qi.
All of these moves, dating back over several iPhone generations, have been made to steer users away from the use of ports, either through providing better alternatives or removing a port-based option altogether. The last obstacle is convenient wireless charging. Apple, like a number of other tech companies, has been investing fairly heavily in "true wireless charging," or wireless charging with a range of more than the inch or so needed by Qi. Once this hurdle has been crossed and the technology exists to charge an iPhone from a hub with a range of, say, three feet, I think that Apple will remove the charging port completely, giving them more design freedom (as well as tighter ecosystem control).
This will leave third-party manufacturers (like Anker) with a choice: make products that implement this new wireless charging standard, or lose out on the lucrative iPhone accessory market. I'm inclined to believe that Anker will make a charging pack that utilizes this new form of wireless charging, and although it won't be nearly as space-efficient as their current offerings, it will be their only option for catering to the new iPhones of 202X or whenever this ends up happening. Maybe Anker will split their product line and offer battery packs that have regular ports, like the current models, as well as a separate line of wireless packs.
Of course, this is all conjecture - I'm just a college kid with an interest in tech. I'm no analyst or anything like that. However, when looking at the behavior of both Apple and Anker over the past few years, this is my best guess as to the future of both companies.