In my opinion, it depends on innovations in breeding and mechanization. The invention of the mechanized tea rollers helped keep the cost of standard tea down even as labor prices went up. The invention of clonal tea had a similar impact. Now the issue is with plucking. No one has invented a machine that can mechanically pluck tea as well as human pluckers can. For now, the process still works using hand-pluckers because of the very low cost of labor and the difference in exchange rates between most tea producing areas and tea consuming areas. I predict, however, that soon the rest of the tea world will have to follow the lead of Japan; investing a lot of money into tea research in order to keep the prices competitive while costs of labor rise and rise, and to attempt to counteract the decline in quality that mechanical harvesting creates by introducing other scientific innovations.
As for human rights, that is a very serious issue in almost all of the tea-growing regions. Under the plantation system, it is easier to monitor and regulate abuses, because all the tea processes and workers are present in the same spot. However, abuses will only be discovered through monitoring, as most plantations are in very isolated locations. This is the idea behind “Fair Trade” certifications and other such oversight programs. However, even with this, there are many social problems in the tea fields. Tea workers may overspend and get themselves into debt with moneylenders, and alcoholism can also be a problem.
Although smallholders are free from systematic abuse from plantation owners, it is also harder as a tea consumer to know if the tea is harvested responsibly, because it comes from so many areas, all independent. So if one farmer uses child labor, and another uses too many pesticides, it can be harder to locate those who are responsible once the tea has all been gathered together. It also makes it harder to tell who is responsible for providing welfare services. On plantations, it is mandated by law that the managers provide medical care for their workers (although whether or not they follow the law depends on oversight), but how could you make such a mandate of a refiner who buys teas from many different small farmers?
Also, when there are new innovations in technology, they are harder to spread among small farmers than among large plantations. Instead of one new improved rolling machine, you would need many. Instead of one field to replant with an improved clone, there would be many different areas, all independent.
It is certainly a complex issue, and I suspect the tea world will go through many major changes in the next few decades.
