I know Tikiman has said that the Volcano pool area may be worked on as early as this fall but I sort of doubt it will happen until next year because the main courtyard pool at GF is being worked on this fall and I highly doubt they'd close both simultaneously (keep in mind, GF guests are being invited to swim at the Poly while the courtyard pool is being worked on).
And even though the GF courtyard pool is supposed to reopen sometime between late November and mid December, I'd expect they'd wait until after New Year to do a major refurb on the Poly Volcano pool, otherwise the pool would be closed during peak holiday season, which would not be in Disney's best interests (much lower opportunity cost for Disney to close the pool during value season in Jan., especially given the Hawaii building will be closed then anyway).
On the other hand, they may put the hot tub in some time this fall (or they may simply wait to do this until they do the rest of the pool refurb - it would seem more efficient to do the latter, but Tikiman has been hinting that the hot tub may go in earlier than the rest of the pool refurb).