Guitar and parts availability shortage predictions
Can you expect a shortage?
Yes, there will be a shortage. In fact, there is a shortage happening at the time I write this in early 2021. What will be difficult to acquire depends on what you're trying to buy.
I'm going to break this down into two categories, complete guitars and parts.
What this means is the purchase of a fully assembled guitar, like the kind you buy in a guitar store.
In North America, guitars made in the USA, Canada and Mexico will actually still be plentiful. It's unlikely there will be any shortage of those.
However, for any guitar made outside of those territories, such as Korea, Indonesia and Japan, getting complete guitars may prove to be difficult.
Currently, there is existing stock. But once that stock runs out, getting new stock might not get back to normal until mid-2021.
Necks and bodies will still be easy to acquire. Plastics (knobs, pick guards, nuts, etc.) will still be easy to acquire.
Metal hardware components and electronics however is a different story.
A whole bunch of things like potentiometers, tuners, bridges, pickups comes from outside North America.
Right now, these things aren't hard to get, but once again, that's because stock currently exists.
However, parts don't run out of stock like guitars do. Fully assembled guitars have a "shelf life" of sorts whereas parts really don't.
For example, if a completed guitar sits in storage for too long, it becomes unplayable and can't be sold. Parts on the other hand can sit in storage for several years and still be as good as the day they were made.
The only thing that really ruins metal hardware parts and electronics is corrosion/oxidation more than anything else. How soon that happens depends on metal type and whether it was treated with anti-corrosion solution or not.
Two more things to take into consideration is that it's rare there is ever a rush on guitar parts, and to the best of my knowledge, guitar parts are never manufactured using the just-in-time manufacturing method. (The car industry uses this method but it really doesn't work for guitar part manufacturing.)
What should you do?
If the guitar part is metal or if it's an electronic, manufactured outside North America and is still available for cheap, buy it now.
For everything else not metal or electronic, you don't have to buy now.