Physical lifespan is determined primarily by two things..the robustness of the produce and the availability of parts if breakdowns should occur. I do not know what Canon's policy is on repair parts, but for most Japanese manufacturers, it tends to be pretty close to 5 years after the end of production. I have a couple of Nikon D300s that still work fine and fill a need for me. But key repair parts are no longer generally available for them. This includes the rubber grip pieces that must be replaced if the camera must be disassembled. So their lifespan, for all practical purposes, is "until they break."

A secondary factor is the availability of newer models which have features that you NEED and which your current model lacks. That one is a little more complicated.

In the case of portable two-way radios, by the way, life span is determined by battery availability. Motorola built a very successful line of two way radios in the early years of this century. When they decided that the life of the radios was over, they simply stopped making replacement batteries available. Because this is a niche market, those batteries are not available from other manufacturers. So the radios gradually become unusable as their batteries fail.

You may have been reading too many dime store novels. "An informed assessment" can only come from Canon. Your second error is that the price will increase if the model is discontinued. Prices go down. If you are considering one then get one and try it for yourself. If you are serious then you need information other than popularity contests. Study the 5 series bodies and see what isn't yet available on a 5 series camera. IF Canon has several NEW features they might see fit to introduce a new model. My version of this camera does not lack anything that newer bodies offer so I won't expect a new 5 body for some time to come. Canon just finished introducing an entirely new type body in the mirrorless camera. All this is just 6 months away from an olympiad. Lifespan? My Leicas were built pre-WW II, and they still function properly. Take care if your equipment and it will last. Technology is more of a factor here than is time. For the immediate future? Look for Canon to introduce several new lenses, mostly in the long-glass area. Patents indicate that lighter and longer might be their new slogan. Power Focus might become a standard future on all new lenses. Camera technology seems to be stagnant, but there are fish to fry so lenses will get greater interest. This 5 model has a huge offering in its menus, it might be around for as long a the original 5, or longer. You will not be disappointed in what it brings to you or for how long it will continue to do so.

What is the BH-02, and what brand L Brackets did you get? If the ball head has a standard ArcaSwiss clamp it would fit any of the standard ArcaSwiss L Brackets from Sunwayfoto, RRS, Kirk, Benro, Sieri, and dozens of others. If it has a propritary clamp, you might have a hard time finding an L Bracket for it from anyone other than the manufacturer of the clamp.

A simple solution if you are really in love with the ball head is to just replace the clamp with an ArcaSwiss clamp. If you are not in love with the ball head, just replace it with a head with an ArcaSwiss clamp. Amazon has 20 pages of clamp options as well as ballhead options.

https://www.bing.com/aclick?ld=e3eDnyqV7uIAra8G1XNOzRkjVUCUyS5_xzSfj1_dBDHb6TS-ArISglykQDB06E2nbpq6A3D8bhLSAO0cIng9XiOfRhJB65RILntkJ3GttTBj6tyOJJRYtrO6elma3Vk3ylpduivE6AIvcIgP9BVg5OEnjid2MoCFLuoqCq8UDtwredO-0K&u=aHR0cCUzYSUyZiUyZnd3dy5hbWF6b24uY29tJTJmcyUyZiUzZmllJTNkVVRGOCUyNmtleXdvcmRzJTNkYXJjYSUyYnN3aXNzJTJiY2xhbXBzJTI2dGFnJTNkbWgwYi0yMCUyNmluZGV4JTNkYXBzJTI2aHZhZGlkJTNkNzc3MjE3ODMxNTgwNzYlMjZodnFtdCUzZGUlMjZodmJtdCUzZGJlJTI2aHZkZXYlM2RjJTI2cmVmJTNkcGRfc2xfOGFmdXRzb2wzdl9l&rlid=0915f9243a98189cb91ea51c9cc19601

There is a lot of good advise here that I can only add a little bit to.First, do visit the panorama section here on UHH and you'll see many panos which you'll find are mostly shot "hand held".
Second, when over lapping my shots I find it incredibly easier to just overlap by 50%. To do that, what ever is in the center of the frame is moved to the edge, rinse and repeat as often as you wish. Doing this also helps your processing program stitch your images without glitches. You will shoot more frames this way but @ no extra cost.
Third, Try not to over think the process and also try to keep it simple. Panos are no more difficult than a single image, just more of them.