These are interesting comments, and I always enjoy thought exercises on RFF.
I'll preface this by saying that I don't believe that cameras are investments, except to the extent they are useful in producing salable output. But that I am also not so rich that I light my cigars with $100 bills. Except at that one club. 🙂
One comment I do want to make in relation to the "sell the body while it's still worth something" suggestors is that if you bought an X-Pro1 when it came out, it is already essentially worth very little compared to when you bought it. Fuji started bundling lenses a couple of months after launch and ultimately dropped the retail price 41% from its start (from $1,699 to 999). This pretty much caps the amount for which you could sell any used X-Pro1, no matter how nice, since you couldn't easily match the 2-year factory warranty. So keeping the body compared to keeping just the lenses is not as big a difference as you think, since it still has value for use as a camera.
Every indication is that Fuji's APS-C modus operandi is to introduce high and drop prices to keep up volume. While this is fairly normal for cheap consumer products, it is a cardinal sin in higher-end products, due to brand equity considerations. Specs might improve with succeeding models, but no price ever goes down. You might drop your production volume, offer post-purchase rebates, or dump product in other markets (Leica has done all of these), but you don't do things that make it look like your products were overpriced in the first place. Techniques like that also alienate those of your early adopters who perceive that they will get burned every time they buy a new camera. And tiny (and incremental - what, 6 cameras now on the same 16mp sensor?) changes that mostly serve to make older stuff less "new" and to depress the resale market don't increase the Fuji love.
The practical effect, though, is that it is highly unlikely that - post X-Pro2 - that the depreciation of an X-Pro1 would ever match the extent to which Fuji forces depreciation by slashing the retail price on new introductions. If you care about the financial end (and I'm not saying I do), you would conclude that you're better off selling the -1 now and buying the -2 when it does not set the world on fire (Fuji has no problem meeting its demand).
So at the end of the day, this may all really be a question of folding or going all-in.
Dante