Andrew R Stewart 

The Op mentions having a "split hub" while on a tour, breaking spokes and seems to be concerned about a bearing failure that will stop function and finding replacements. I've commented on design a bit but here's my opinions on the 'while on a tour' stuff.

Very few hubs fail compared to other wheel aspects. Very few. Flange life is generally really a long time as long as radial spoking is avoided. Hub splits or cracks in AL shells are way down the list of likely issues. Axle break or bending far more common, generally only found on rear hubs with significant bearing location off sets (dishing, from a rim's view). Bearing degradation is usually a slow process, lack of periodic maintenance helps speed up this process as does extreme exposure (water, grit). I have found that most all claims of bearing failure being sudden are because the rider didn't pay attention and take care of the gradual wear and tear with maintenance (cleaning, relubing the bearings if not replaced and good preload adjustments). The rider only notices the bearing when it is so bad that the performance is affected to a significant degree. I often describe this to getting a cancer diagnosis. The cancer has been there for a while and only after growing big enough will the rider notice.

Now when we talk about on the road repairs of bearings (independent of why) we need to look at availability of parts and ability to do the work. Cup and cone bearings are not widely available in many areas, pretty much the only stores that deal with them are bike shops. Premanufactured cartridge bearings , on the other hand, are widely distributed via a large number of different industries and can be found in car/motorcycle repair joints as an example. These bearings are generally made to many industry wide dimensional standards and have a huge supply chain presence. The math favors being able to source a cartridge bearing over a cup and cone. Installing cartridge bearings is a job that way many people do in a variety of jobs. Cup and cone replacement and readjusting of preload wants the proper cone wrenches. With so few bike shops dotting the roadsides in most countries this means the rider is now also carrying cone wrenches along with the bearing spares. The big reason why the bike world still uses cup and cone bearings is because of manufacturing tolerances being able to worse. So a hub will work well on a frame that wasn't well built, cup and cone tolerate misalignments better than cartridge units do.

Spoke breakage has nothing to do with hub bearing design although is a problem for those who don't stay on top of their equipment. I've carried spare spokes on all my tours, of any real distance, yet I have never needed one after 10,000+ miles of loaded tours over 40+ years. Not to say that one won't need spokes or that carrying spares in not a good idea,, just that well taken care of bikes generally don't suffer fatigue spoke breakage until after a lot of miles.

I don't think any of this will change what the OP does though. We tend to have tunnel vision as we do stuff. Andy