Unless the report of "screen lamination issues" is true which could easily push the date back to September or October.
well screen lamination issue, can't be of the exact same screen as we have now.....they can't suddenly not manage to make the current screens. So, that at least means better screens in some way, anti glare, retina or whatever...which is more than a spec bump IMO.
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would be funny though if out of the blue tomorrow we have new simple spec bumped iMacs - and all the claims and analysts just got screwed over by apples double down secrecy