I'm not being pessimistic, (well maybe i am, but who can blame me after waiting half a decade for 2.0 final?) but isn't all that code talk going to be a huge project which will require even more resources to develop than 2.0? I guess a sensible ETA for 3.0 would be seriously not before 2020. 3.0 doesn't seem to be a fork of SMF but something quite innovative, and all the years i've been here in this community, i've learned (painfully) to dread the word "innovative" as it either meant impossible to make or several years to release.
As for 2.0 and subsequently 2.1, why not concentrate the current efforts to fix all those hundreds of bugs from the tracker before moving on to develop 3.0. As an admin with several forums running on SMF software, i would be much more at ease knowing that most of the bugs are fixed, so even if it takes a decade to release 3.0, i'll be at peace and wait for as long as possible. Obviously, if it takes 10 years then i would most probably be using another forum software by then as the SMF software would have become outdated.
Honestly, this announcement feels like an incredibly risky move, knowing the gigantic/desperate problems and record-breaking lengthy development time that the SMF community suffered before 2.0 was finally ready. Don't get me wrong, i care a lot about SMF and i definitely love the ideas here, but without a rock-solid foundation and a sufficiently large number of developers on the SMF team, that project is going to cut all the air out of the current 2.0 and 2.1 project, making everything come to a stand-still and maybe even alienate many team members like before. Oh no... The nightmares are rushing back!
The SMF development team needs to rebuild itself and gather together all the great minds here before going in to tackle such an ambitious project for 3.0. I really want 3.0 but then i would rather just get constant updates every few months than wait 5+ years for an unfinished product. I believe that the average time for a new version should be 1-2 years at most, based on development time at all the other major forum software.