I'm thinking yer OWS hippie, slacker delegate will have been disenheartened, just as you predict. What I'm waiting for is the unions -- SEIU, AFSCME, you name 'em, and the LaRaza/Mecha contingent -- to up the ante.
Yes, the DNC convention will be a mess, but I don't believe that'll be the worst because the summer/fall is the last gasp for putting this particular machine in gear.
If I'm wrong, I'll be glad to be so.