I think Cataclysm is going to have enough raid content right off the bat that raiding players won't HAVE to run heroics every day, it may be more efficient for them to simply raid one of the 4 or whatever available raids and skip heroics all together once they out gear them, kind of like how things were in TBC.
But then those at heroic level or trying to break into raiding can still use heroics to "catch up" and such.
Blizzard admitted the badge system and heroics were a mess in Wrath, forcing you to do heroics throughout the ENTIRE expansion because they kept upping the badges and badge rewards for heroics.