Just not that many...
After reading this thread for several weeks and having just returned from a 400 + mile trip to and from the Dallas/Ft. Worth Metroplex I must comment:
I saw only 4...count them one, two, three, four T-Birds on the way to and in the Metroplex. Red, Yellow, Black, and White and then the PCR I was driving. That's not a lot. How many Mustangs, Vettes, Boxters, and Z3s did I see? Lost count - everyone in the DF/W area drives BMWs it seems. I had loads of people pass me in SUVs and wave and smile - seemed like several BMW drivers passed me slowly enough to give my T-Bird a good look.
Ok, lets fast forward to 2010 (only 5 model years from now) - if FoMoCo stops the Bird in say 06 or 07, by then they will be sought after - don't get me wrong - they will not go up in value for a lo-o-o-ng time if ever, but the slide in value may be much slower in as little as 8 model years from the start of production! I agree - don't buy anything with wheels less than 30 years old as an investment. They will usually disappoint you.
I saw the end of the C4 Corvette era in 1996 and less than 10 years later, the C4s that were garaged, had premium care, were limited in production, and can no longer be seen coming off the assembly lines are holding their prices (Case in point the 1996 CE or Grand Sport with the LT4 engines). The LT5 ZR-1s are up - way up in value and now are beyond new list prices - remember this was the "special" DOHC engine made by Lotus I believe.
If your Bird is not a daily driver and you garage it for a few years (be sure you drive it some...that's why we bought them) while taking good care of it I think it will be sought after - how much remains in the view of the buyer. If it is recognized that you can get a low-mileage T-Bird that has a Jag engine and suspension that is no longer made then they may resell well. But, I bought mine to drive, enjoy, and KEEP as has been said here. Some day soon the Ford Dealers may well be saying "Remember when we had those shiney T-Birds on the lot...wish we still had 'em".
Happy Birthday America - you build the greatest cars!!!
Mike