Kevin Lynch, moderator of the Bioware forums, in the ongoing stickied BG3 thread, part III:
"This is Part III of the most recent of BG3 threads here and there. Please take the time to browse through those threads, as they have various tidbits of rumour on BG3 that you may be interested in reading.
"Some basic "facts" about BG3 are that Atari has stated there will be a BG3 (uhhuh), there is no developer announced (which I would suggest means that the game, if being developed at all, is incredibly early in the development cycle; probably not at all), BioWare states they are "not currently working on a BG3", and that anything released about what is in the game (by Atari reps, for instance) are quite likely to change by the time the game comes around (which won't be for a few years at the earliest, considering the development time required). Anything besides the above (and including the above ) is pretty much just rumour, so take everything fairly lightly.
"Feel free to discuss anything related to BG3 here. Any other BG3-related threads opening in the forum will be locked. A reminder: once BG3 has an announced developer, all BG3 threads will be locked and/or moved to the Off Topic forum. Until then, have at it."
in my mind that makes it way too early to even speculate about it. however, consensus is that it will pre-date the BG1/ToSC/BG2/ToB era. again, remember to take everything with a grain of salt.
and play the original series to keep your fix going.
V***V