I spent many years as a PM for another security company. One of my products was a cellular mobile DVR. My sales guys wanted more and more cellular products, so I spent a lot of time researching them. I also worked for a cellular retailer for many years so I'm familiar with the industry.
Short version is, don't hold your breath on an integrated cellular camera. Even if you see one that says it's 'LTE' you probably shouldn't bother with it. (unless someone comes out and says specifically 'certified for use on Verizon', which isn't likely. The exception is Reconyx still cameras)
Long version: "LTE" is a very generic term, sort of like 'Cellular'. If you get into specifics, there are several different frequency bands within 'LTE' only some of which are actually used in the USA. Since most of these products come out of China, they are coded for Chinese LTE bands. This was the same situation with older GSM products. So, pretty much anything you are going to find that says 'LTE' is probably not going to be set up to work on bands for the USA. I mentioned Verizon earlier. They are SUPER uptight about allowing anything on their network. The process for getting a product certified to be used on Verizon is very extensive and very expensive. An Asian vendor isn't going to bother. Reconyx still shot cameras have a Verizon certified product, which is one of the very few I've ever seen. Still shot over cellular is a lot easier to do than video.
As was said earlier, if you really want to do a cellular camera, use an external modem (like a Sierra GX440 or Cradlepoint 650). They are much better about keeping up with current USA cellular devices and are approved for those networks.
Just be aware that streaming video is going to eat up a TON of bandwidth. Almost all providers have data caps. In the Law Enforcement world, Verizon has special 'unlimited' plans for data but in the commercial world, you're going to have to turn the bit rate down really, really low for 24/7 streaming. Also you do run into some port issues sometimes and getting a static IP address on an aircard isn't impossible, but it does take some work (and for commercial customers, there is usually a fee to do it, on top of additional special programming with APNs).
I have a client that is using an Axis dome camera and an Pep Link cellular modem to view remote hog traps on ATT. He isn't streaming 24-7 though and he's still having data cap issues from the few times that he actually does log in to look at them. It works and works pretty well, but the learning curve to set up the port forwarding and getting the programming from AT&T tech support took some time.