I personally think that El Salvador will be a dramatization of the Bitcoin era, and they will set an example for other countries, companies, and even individuals. This investment will play out in one of several ways:
1. El Salvador sells all of their Bitcoin for a huge profit, and the president looks like a smart guy, and then they move on.
2. Bitcoin crashes in price and El Salvador takes a huge financial hit, then they vote out the president there, or worse.
3. The current president gets voted our for unrelated reasons, and the new regime sells the country's Bitcoin at a profit or loss.
4. Some corrupt official(s) there mess around with the country's Bitcoin holdings and "lose" it etc.
There are probably other scenarios.
One thing I don't think people understand is that investments have one purpose: to make money. You buy low and sell high, and then use the profits to improve your life. Hence, the idea that El Salvador or anybody else would hold on to their Bitcoin "forever" is just plain stupid. That's not how it works.
The second scenario is highly unlikely. From what I've read, El Salvador's average purchase price is somewhere around $50,000. Bitcoin is up to $100,000; there's no way it's going to crash below that. It's possible, but judging by the current market situation and from what we've seen, I highly doubt it's going to happen. Either way, El Salvador has profited from their investment, so no matter what happens, they're going to be in profit, and people have been praising this move, even though he received a lot of backlash when he first purchased Bitcoin.
As another user already mentioned, El Salvador is not the first country holding Bitcoin, nor does it have the largest supply. Bhutan has a lot more Bitcoin than El Salvador, but it's hardly discussed in the forum. In fact, I don't recall seeing a single mention about it. Thus, even if they sold all their coins, it would hardly make a difference in the market, and if there is, it would be temporary due to FUD.