Whoa!!! Holy crap!
Not that the Windex won't work (because it probably will) but this only Future we're talking about here! We're making this way too complicated.
Hot water, and wash cloth that's it! Future is liquid acrylic for goodness sake, it's not enamel or lacquer! I mean, seriously, if the stuff was that permanent, why would you have to keep applying to your floors? And that's also the basic solution for removing old decals, Futured or not. Just use a hot, wet wash cloth and press and hold, then rub. Repeat. Nothing more complicated.
Worst case scenario, you could use a toothbrush and some liquid dish washing soap to really get under the decals and get them off.
Now if you're looking to complete strip the model future, paint, decals and all, Easy Lift Off (ELO) if you can find it. From what I understand, it's been discontinued.
"Never mind...it's just easier to call you stupid." -Brian Griffin