Or, CRAZY IDEA, Nintendo could just send out a 1MB software update to add a Settings option that would allow you to re-mapp the new datum (neutral starting point) for a specific Joycon's thumbstick. Bam, fixed in 30 seconds. Tadaaaaa~
I once had a similar problem with one of the triggers on my XBoxOne Elite controller not working properly. That thing was expensive, so I was pretty concernd at first. But since it came with software to adjust its behavior, I was able to change that trigger's threshhold of activation and fix it myself rather than sending it off for a hardware fix or replacing it.