Well if this was a business I was considering buying, I'd throw this out:
-the LaF is probably the safest bet. The big risk to that is the internet age and people my age and younger getting tired of Ferrari's antics or having a bad experience with Ferrari and losing faith in that particular religion. For example, I bought a shiny red Ferrari once and the ownership experience was such that I tend to disbelieve the positive reviews of the 458. So far off of test times and magazine commentary was the Fezza I owned. So far off.
The risk in the LaF is that Ferrari's eventually cost-counts and lies its image into the toilet. For example, the late 60's muscle cars people were paying a million bucks for 5 years ago... nobody my age is going to pony up a million bucks, inflation adjusted, for them. These are cars selling to people who dreamed of these cars as kids and, now, as old men, finally have the means to buy them. Few my age shared this dream as kids. The people paying huge bucks for vintage Ferrari's... if Ferrari loses its rep, will these cars gain (again relative to inflation) or hold value going forward? Thats the risk here - Ferrari's rep. If Ferrari maintains its rep all will be well for LaF buyers.
-The 918 will certainly depreciate greatly, where it will settle ... I'll guess 500k. And the batteries will become the CGT's clutch, so to speak. 6:57 is a nice time, but I don't find it shocking or stunning in a world where LFAs and Vipers and C7 ZR1s are within any kind of sight of it. Or a Nismo GTR is probably withing spitting distance?
-The P1s fate hangs in teh balance. If it set a dominant time, like the 6:3X rumors, and begot a line of McLaren cars that built a history like Ferrari or Porsche or Vette or Lambo have, it would appreciate. If it winds up an underachiever ... huge depreciation.
It looks so fantastic, so new, so unique, if it delivers on that promise its prices will be fine. But lets face it, today, in this cars time, an obsession with the fairly pointless thing that "manufacturer stated and unverified" ring times are, if it doesn't turn in a huge win in stated 'ring time, it will depreciate greatly.
Thats my take on the market. If this was a security I wouldn't touch the P1 either way. If forced to, I'd sell it. Emotionally I want it to live up to all its promises and more, its the underdog, the new guy. Porsche is boring, bean counting, overcharging, over profiting laze. Ferrari are ... underachieving liars with amazing mastery of the press? I've never felt as short changed in my life as the Ferrari I owned, save, perhaps, a couple of shiny but substanceless girlfriends.