the simple solution is a better fee priority formulae..
that way you dont have to decrease the blocksize that hurts everyone should in a fortnights time demand picks up again but hits the decreased wall.. (as thats just silly)
but if the block remained at 4mb but was 'empty' it would cost a spammer a hell of a lot more to fill it. compared to a block that decreased to under 4mb
by decreasing the blocksize means he can fill the block with less transactions. which is stupid aswell as all the complexities of trying to avoid the rescan orphan things i said before
a better fee priority mechanism ensures the spammers pay more for spamming every block while not causing issues for the normal folk
Well, I did ask:
Was
Litecoin's spam fix ever implemented in Bitcoin? And if not, could we look at implementing that as part of this proposal?
which is related to fees making it harder to spam, and then the thread died for almost 3 days.

But yeah, let's look at the fee priority mechanism as well. Each level of security we can add makes it that bit more robust. But I'm reluctant to drop the reduction aspect in the same way I'm reluctant to adopt Carlton's fixed upper cap. I sincerely doubt you'd accept his idea and there's no way he'd accept yours, heh. Both views are a bit too far towards one of the polarised extremes. In order to be a compromise, I'm trying to steer this thing somewhere towards a happy middle-ground.