There were reps who said the Pokemon Sun/Moon bans were also temporary, so take that with a grain of salt. Nintendo has also said in a statement, "This ban is effective immediately and requests to remove the ban will not be processed," which seems to suggest that it's permanent. Considering these things, the fact that Nintendo has apparently been working very hard to setup this banwave, and the fact that Nintendo has no incentive to unban CFW users, it's probably permanent.
The only odd thing is that banned users still have access to the eShop. I personally think that says less about the duration of the ban and more about their internal decision making process regarding the kind of ban they wanted to impose. Ignoring the Pokemon Sun/Moon bans, there are historical accounts of 002-0102 bans that have been permanent but without an eShop ban.