Without moving to CF, I'm pretty well set on tripods. I can always use another light stand, though.
I like the idea of light modifiers. First, that's another one of those things that seem to collect in the studio. Second, they can and do wear out. I've re-stitched one of my umbrellas multiple times at this point. I wouldn't mind replacing it. But I know this won't be everyone's thing.
I'm curious to see what studio strobes wind up in drops, if that happens. I'd also toss in off-camera flash units like the ones from Yongnuo. They won't break the bank, and having extras is always handy. They're a good entry to strobe photography because a three light setup can be had for less than a new lens, typically.
The more I think about it, the more I wouldn't mind seeing pretty much everything else you mentioned, too. I've got shutter releases in my bag, but I'm mean to my gear (just ask my umbrellas!) Having avenues to buy replacement gear would be nice.