How do you see the collectibility/pricing difference between low mile cars and driver cars over the next 5-10 years?
Sounds like you are still struggling. First, any answer to your question is pure speculation.
Let's start with some perspective. 4,038. Not even one for every Ford dealer in the US. Rarity established. By most accounts, possibly 1,000 crashed. Of that, some hundreds totaled. Many exported to nouveau riche Russian mafia and the like. More than six years gone since the last came off the assembly line. Rarity moving into threatened species status.
Next. The most amazing car ever produced in the US. Stunning when new. Stunning today. Will be stunning still in 40 years. Women will come on to you with their husbands standing there. Then, their husbands will come on to you. This isn't a joke. This happens. Every owner of every other exotic wants one of these. Most will tell you. The ones that don't say it still want it. Go to any cars and coffee and person after person will say you have the most beautiful car there.
Drive down any street and people gawk. Small children stop and point. Small children! It is amazing. Everyone just wants to touch it. Very annoying, but absolutely phenomenal.
So...we've established the GT as a rare object of extreme desire. What else?
Well, what else is that because of the rarity, the market is effectively cornered by a handful of exotic car dealers. They are the market makers almost as De Beers is for diamonds...except they don't own all the stock. However, when a choice GT is privately offered for sale, they can be there with cash. Therefore, to a great extent, they establish and support prices. (Note: I hope it goes without saying, this is opinion. Further, I make no judgements. In fact, personally I think of it as favorable, because reputable dealers add value and earn their profit.)
You have already heard from everyone who has chimed in that these cars were meant to be driven. I think Ralphie said it simply and best...the pleasure he has gotten is worth $500K.
Now, back to the question on collectibility/pricing difference/low mile cars/driver cars. Ahhhh...I'm sorry...I am emotionally spent and that is just too banal. Bahahaha!
Once again, good luck. But I still think you are at cross purposes between wanting to drive and wanting to sell in a few years, and meanwhile the owners are just having a blast driving and the prices continue to climb.