1. Modern guitars are made exactly the same way that vintage guitars were made in the old days.
I'm not sure I'd go with "exactly", but in many ways, the differences are better: CNC machines make the same pieces over, there's years of research into pickups, and environmental regulations push poly over nitro. To be sure, some raw materials were available to C.F. Martin and Lloyd Loar that are less available now. Especially for electrics, I'm convinced that the electronics are far more important than the woods, and electronics have been the subject of decades of improvements.
2. Anytime you are buying something used (vintage) you have to worry about the provenance.
Did Eric Clapton really play this? This is where distinctive instruments, like Clarence's double-wide Tele and Gretsch-necked D-28 come into play. Any picture can establish that connection, or the deeply-damaged finish of Rory Gallagher's Strat, but a blackguard '52 butterscotch Tele looks like any other.
3. Extreme valuations are causing counterfeiting.
4. There is NO guarantee that vintage guitars will hold their value.
I'm torn by this. There'll be fashions in guitars, like the Stratocaster becoming bigger in the 70s after Eric Clapton made Layla or the Les Paul returning after Slash. I think there will always be a value for the older instruments, but I don't think that this value will always be in the tens if not hundreds of thousands of dollars.
5. How do you protect and insure a valuable vintage guitar collection?
Pribek linked to a story recently where a classical violinist forgot his (but actually not his) Stradivarius violin in a taxi. Strads are crazy valuable, far more than even the most valuable guitars, but the extremes are good for discussion. In a related concept, my dad used to have a sky-blue 1957 Thunderbird, and he couldn't get more than liability on it because otherwise he couldn't drive it or keep it in an unpadlocked garage.
I read that James Burton keeps his paisley Tele in a locked vault because it's too valuable to keep at home. This saddens me somehow.
6. Nobody Cares But YOU and a few other guys that haven’t discovered girls yet!
The value of a thing is determined by how much someone would pay for it. It's pretty much a shared hallucination. That's pretty unstable, eh?
7. There is too much of a disparity between wholesale and retail value in the vintage guitar market.
8. Is a guitar more valuable because a celebrity owned it?
Consider how many people didn't go to the last Police Squad movie because
9. Guitars are just tools.
If you had a wonderful golden-era flathead screwdriver with special alloy tip and rare rainforest handle, you might be so careful with it that you'd never tighten screws.
Anyway, read the article and consider. And I'll hold onto that sixties double-bound sparkle Tele you have while you're considering it.