People waiting for clearances is a sign of actual demand though... If they really wanted it for $x, they'd pay it. If they don't, they wait, whether they find it or not. I tend to see very little of people kicking themselves over NOT finding something on clearance, and more that if people wanted it badly enough they bought it while others either waited and got it or missed it because demand just wasn't as strong as it may seem to a handful of us.
I'd love a Death Star... not sure I'd like the spherical one shown on Vic Wertz's panel myself, as it's sort of "different". Reminded me more of an AF type of playset, but if they did something akin to a stackable playset... Maybe one you could even connect multiple sets together side-by-side and atop one another, then to me that's great. Sadly though, for those who want things like this, the big stuff doesn't have that strong a support in the general collecting community I think. Not from what I see... Stuff wouldn't go to clearance if people wanted it that bad.
G.I. Joe has two luxuries in its favor Star Wars doesn't. They have had stronger sales #'s generally, and of course they're Hasbro's property to begin with. Believe it or not, Joe has done very well, even with a slump last year+. Star Wars has had some very bad times though... two years of film toys that either did flat out poorly or didn't meet expectations, and then non-movie years that weren't a juggernaught of sales.
I think if ROTS really makes a big impression, larger items are more likely as there's new people involved in the hobby to drive it, but till then I think we'll be more apt to get a Cloud Car and Cantina endcap before an AT-TE...
I will say, if you got to see the Lucasfilm Archives exhibit (one of the more consistantly LONG lines in the event), the AT-TE they had on display is almost dead-on 1:18 scale, and so was the Millenium Falcon model. OOOOoooo baby! I took lotsa detail pictures for "future projects" hopefully.