On a scale of 1-Clapo I probably rate about an 8.5 when it comes to Johnson fanboyism, so you can take this with a grain if you wish.
I don't think the guy should be dropped for Adelaide. Put simply, I think he's one of our 4 best bowlers, and has proven so consistently over a large enough sample size. Dropping him because he's been in average (but hardly terrible) form for the last 6 months and just had about the worst game of his career isn't really looking at the bigger picture for mine. Fact is the guy is one of the few players we have that can even semi consistently tear through international standard teams when in form.
He was rubbish in Brisbane, but he was hardly alone. Siddle, Hilf and Doherty didn't take a single wicket in the second dig either, with two of those only getting gifts or a slogging tail in the first innings. The catch and his duck made his game look worse that it was, but lets face it, the guy is hardly there for his batting, and dropped catches happen to the best of them. Ask Clarkey.
If he is to be dropped I hope it's done with a view to getting his head in the right frame of mind for a return in Perth or possibly Melbourne. If his head is the problem then we should be doing what we can to get him right so he can bowl at his best. We shouldn't forget that he's too good to be junked on the scrapheap with the Cullens, Krejzas or McGains of this world.