I'm still regularly playing and running D&D 3.0, Arcana Unearthed/Evolved and Stargate d20 in my two game groups and moderately enjoying it precisely because whilst we've added LOTS of setting variation from published material, core rules-wise we haven't added much beyond the original core 3.0 books...
Indeed. Assuming the published version is close to the playtest draft we saw, one could run a game with BRP that from a rules point of view resembled the original BRP pamphlet. Alternatively, pick the right options, and you could have something that is nearly indistinguishable from RQIII, but has X-Men level powered Super-hero's...
My immediate plans for BRP are to re-work my (currently on hiatus) "After the scouring..." post-apocalypse England RQIII setting in to a BRP form, plus further work on the "Gate Warden" SF setting I used during the playtest, and a few fantasy settings(Gwenthia, what I used to call "fantasy Mars" and a Fantasy/Horror hybrid called "the Last Refuge"). How far I'll get with any of course is another matter (fewer 9.45pm nights at work would probably help...).
Personally, I don't see huge need to revise BRP, as I'm very happy with the synthesis and development of prior work Jason has achieved - but once the core book is published, it wouldn't be a tabletop RPG if people didn't start house ruling and changing it.
As for forums here - can't really comment fully as I don't get here enough at present. Given the title of the site, I don't think a HeroQuest section makes sense:its different game and has support; what nest, a GURPS or d20 forum? Once the BRP book is out, adapting to the interests of subscribers as to which settings they use and discuss makes sense - I'm not personally convinced that many will use BRP with Glorantha (if they are that keen on the old way they have RQIII, otherwise they have MRQ which has it's own forums, which is also where discussion of new MRQ Glorantha material will tend to gravitate), but if it IS a setting people use with BRP don't see it being a problem.
Cheers,
NDM