In terms of numbers built, the MP4-12c is closer to the 599 GTB than the 458. I would expect a similar depreciation curve. Probably 5 years before the MP4 dips below the GBP 100k mark.
Interestingly, front-engine V12 Ferrari's (both 2+2 & 2-seat ranges) depreciate at a nose-bleed's pace 'stateside.
The mid-engine V8 Ferrari's depreciate very sparingly, before leveling-off & settling-in at a price-point slightly above their predecessors. The ownership year-1/year-2/year-3 values are particularly strong for these models, even above their sticker-price, as market-adjusted pre-owned models go for $25k-$50k above what can be ordered brand-new
via dealer (due to Scuderia shenanigans, walking-in & ordering generally a difficult thing to do for the layman even w/ means/pocketbook).
I believe the MP4-12C will have a very strong residual, 'stateside. There's a sizable non-Tifosi crowd who are true gearheads & w/ means, as well as the novelty of owning a McLaren; not to mention the minuscule #'s of MP4-12C's relative to Gallardo's, 458's, R8's, etc. And, but of-course the all-world performance/handling, woot-woot!
Another point worth pondering is how & if/when the P13 may affect MP4-12C demand & so on.
With all that said, resale/residual/etc is largely a moot point for me w/ regards to the MP4-12C. This is gonna be a keeper for me, and a very unique & coveted experience (following the concept, awaiting the release, spec'ing/acquiring, getting a literal game-changer & as well as it coming from a man/principal/company/philosophy that I just revel in, all in real-time as it was happening). I don't see myself getting into the hypercar realm in this lifetime where I can duplicate such an escapade. So, I'm gonna enjoy & cherish it for all it is! 2012, oh yeaaa...